It's a bit more complicated than that -- in fact, the enormous range of French ancien régime noble titles is very confusing.

I'm not sure how much you already know, so I'll give you more than you need to know. First, the classic in the 18th-century field is Franklin Ford's 1953 Robe and Sword, and while (as its date suggests) a fair number of its argument are to be repudiated, any consideration of the history of French nobility needs to also consider these questions of conflict and tension. I'll return to this in a moment. To more directly answer your question, it should be noted that splits within the nobility were not as simple as the oft-evoked binary between the Robe and the Sword. It’s difficult to explain better than what has already been written, so I’ll quote at length from Gail Bossenga’s chapter in Doyle’s [ed.] Old Regime France, who deals well with stressing the plethora of divisions that marked the nobility by the 18th century (pp. 57-62):

At the summit of the entire kingdom stood les grands, the great Court nobles of ancient feudal lineage who owned extensive land in the provinces and enjoyed extravagant annual incomes ranging between 50,000 to 250,000 livres. Although these nobles set the tone for the aristocratic lifestyle, they represented only between 1 and 2 per cent of all nobles. Rich nobles who lived in grand style in the provinces formed the next 13 per cent. Another quarter of the provincial nobility lived in comfortable circumstances that allowed them to entertain and keep servants […] A second group of nobles who wielded great influence at Versailles were the financiers, men of great wealth and relatively fresh ennoblement, who served as bankers to the king. […] Serving as an army officer was considered the most honourable and aristocratic occupation, and at the end of the old regime 90 per cent of army officers were noble. Inside the army, however, nobles were deeply divided, because private wealth and court connections were needed to advance an army career […] The nobility of the ‘robe’ formed another important sector of the second estate. These were nobles, so-called for the robes they wore, who owned judicial offices, particularly in the parlements, the thirteen sovereign courts of appeal established by the king in the provinces. […] The sale of offices also facilitated the formation of powerful dynasties at the centre of the many parlements, and prevented advocates who worked in these courts, no matter how brilliant and hard-working, from being promoted to a magistracy on the basis of merit alone. In the sixteenth and seventeenth centuries, nobles of the robe had frequently been characterized as upstarts and even ‘bourgeois’, only ennobled by virtue of possessing high administrative and judicial office. By the eighteenth century, many parlementary nobles controlled vast landed estates and boasted well-established aristocratic pedigrees. In the century before the Revolution, only 19 per cent of those entering the French parlements were non-nobles; 50 per cent could flaunt four or more generations of nobility […] These extravagantly expensive offices, which cost approximately 120,000 livres on the eve of Revolution, were particularly attractive because it was possible for a businessman to continue to run his business affairs while he held the office, and because the office conferred first-degree, that is, hereditary or transmissible, nobility on the office-holder and his posterity after twenty years of service or death in office. Other, less prestigious ennobling offices required two generations to serve in office before conferring transmissible nobility.

If you’re interested in this last point on venality, have a look at some of William Doyle’s books; he’s perhaps the best living English-speaking historian on the 18th-century French aristocracy, and his works on venality have been especially influential.

To return to my initial mention of Franklin Ford: he, Bluche and other contemporaries consolidated the traditional view that, during the eighteenth century, via mechanisms like marriage and the sheer process of accrued generations, the Robe and Sword became increasingly merged as they acted in concordance in protecting their privileges against the monarchy in resistance to taxation. As such, according to this now-classic interpretation, the distinctions between the Robe and Sword paled in regards to ideology, wealth, and lifestyle throughout the century. With the benefit of scholarship’s hindsight, the thesis is exaggerated: other historians, notably Bailey Stone (but echoed by others, including Bill Doyle and Jay Smith), have refuted some of these claims by examining the Parlement de Paris in the pre-revolution (from around Louis XVI’s ascension in the 1770s right up to the convocation of the Estates-General in 1789) and identifying these still divisive tensions between the two. Splits were particularly evident because of levels of education, which -- unsurprisingly, when you consider the philosophes origins of the Robe -- differed between the two, and as magistrates, they certainly continued to bear some resentment against the old aristocracy. Doyle (Aristocracy and its Enemies, 2009) provides some cautions against taking this side too far, on the other hand:

Never united among themselves, the nobles of the robe elaborated no distinct ideology of institutional power to challenge that of their master and creator, much less a rationale for the independent authority of the nobility as a whole.

All the same, he also concedes that:

... [aware] of their ultimate powerlessness […] increasing numbers of magistrates [dreamt] after mid-century of a new structure of provincial power -- or rather the generalization of an old one. Over perhaps a quarter of the kingdom, the monarch shared power, rather than delegated it, with Estates […] Few robe nobles sat in Estates, and in some, representation was explicitly confined to men of the sword.

Thus the Sword significantly outweighed the Robe in elections to the Second Estate in 1789:

The great losers were the robe nobility, who for most of the preceding century had been the order’s only spokesmen, and kept the wheels of government turning too. Sword nobles had always looked down on them, even as they envied them their power. Now they had their revenge. The biggest single group elected by an order which still liked to justify itself by its military vocation were serving or former officers in the army or navy.

I know this addresses more than just your original question, but it's hard to limit a response to the rather ambiguous term of 'pre-Revolution' (which could imply many different chronological categories), and the whole debate over tensions or unity is also quite fundamental to understanding the nobility's varied natures at the time.