I'm assuming this question refers to the European Revolutions of 1848, so this answer pertains to them. Also note, that the Revolutions of 1848 were a massive event in European history, so I'm painting with a very broad brush.

The political actors of 1848 were a highly heterogeneous lot whose political opinions ran the gamut of utopian socialists to socially conservative monarchists. In general, historians divide the revolutionaries into two major camps. On one hand, liberals represented a more conservative approach to revolutionary change. Liberal politicians tended to be champions of constitutional order and a strong legal order. From the perspective of 2015, the liberal program seems rather milquetoast but liberalism's championship of the constitutional limits on the executive, enshrinement of legal rights through a constitution, and the idea that law was sacrosanct was quite at odds with pre-1848 European governments.

In 1848, some liberals made common cause against the Vormarz order with the more radical elements in European politics that wanted a broader political leveling. This political alliance shared a common enemy in the form of the reactionary European governments, but diverged over several key issues over the course of 1848. Political radicals, as exemplified by the young Karl Marx or Friedrich Hecker, saw the revolution as a chance to enact a major restructuring of European government. These democrats favored universal male suffrage and even went as far as championing a republic over a monarchy. While the radicals' position won over some liberals, conservative and moderate liberals were leery of extending the franchise beyond property owners. Furthermore, some liberals were distrustful of populist politics and were more than willing to compromise with the monarchical order. Nationalism also emerged as a major wedge issue in 1848 as liberals tended to argue for a new state based upon national lines whereas radical democrats tended to waffle on the national issue.

This political divisions allowed for the reactionary forces of the pre-1848 to get a second wind and defeat much of the revolution. The result was that many of the radical democrats were exiled. Marx went to Britain where he wrote much of his famous theoretical work, and Hecker and many other German democrats went to the midwestern United States where they became one of the stalwart champions of Free Soilism and other progressive causes like abolitionism.