Right, to answer your question I'm going to go through each layer of the social hierarchy in Anglo-Saxon and Norman society.

Let's start at the top with the king, in English society he was appointed by the Witan from the royal house, it was not a strictly hereditary title, allowing for example for Harold Godwinson to rise to the position. Lesser kings could be 'vassals' (though this is a feudal term) to their more powerful counterparts. Norman kingship was strictly hereditary, furthermore, kings were equals in position, the only way a king could be a vassal was if he owned land in another kingdom.

Below the king was the ealdormen. These acted in place of a king governing over one or more shires aided by reeves, they were responsible for raising a fyrd (local levy) and served on the Witan. They had increased in power following Sweyn and Cnut's reigns after whom some ealdormen began adopting the title of eorl, equivalent to the danish jarl. These held power over multiple regions, but were still answerable to the king. This was changed after 1066 as the Normans introduced the feudal hierarchy to the nobility, expanding the noble class. Furthermore, the new aristocracy's responsibility changed to that of raising taxes and providing knights for the army.

Underneath the ealdormen stood the thegns. This was also a position greatly reorganized after the Norman conquest. Thegns were principally local, tribal chieftains rich enough to buy their own arms and armour and therefore serve in the army under an ealdorman or lead their local contingent of the fyrd, however their role was mostly municipal. On the other hand the knight who replaced them was primarily a military figure who served the local lord and were rewarded with land.

As we move on from the nobility, I would quickly like to point out, that while alterations to the noble classes weren't exactly revolutionary, the entire ruling class of England was replaced by foreigners. This had huge consequences on law culture and language.

more changes were made to the position of the lower classes, in Anglo Saxon times, this was comprised of 4 main groups. Churls (freemen) split into geneats, kotsetlas and geburs (peasants) and Theows (thralls, slaves).

geneats correspond closest to feudal yeomen. They were free and worked their own land, they were expected to serve in the local militia in a thegn's household guard. If a geneat was rich enough or proved himself in war, he could attain the status of thegn. Yeomen could not do this without first becoming a squire, usually given to children of other knights.

kotsetlas had different duties depending on the estate, they did not have to pay rent on their land and were above geburs, but did not need to pay rent. typically they served as specialized labourers or as guards. this class was not recognized as different to the Normans, who lumped them together with the geburs.

geburs were effectively peasant farmers who was under the protection and worked the land of the local lord in return for rent which could be paid in labour as well as food or money. They were afforded much more rights in the times of the Anglo Saxon and could serve in the local fyrd. If they prospered, they could climb the social ladder. The Normas stripped many peasant privalages, however could never push through the french feudal practice of tying peasants to their land, needing permission to leave.

finally are the Theows, slaves. These were more like indentured servants to you and me. They were employed as farmhands and servants. They had it pretty hard, but could buy their freedom and even own property. most people became slaves by being born a slave, debt or war. Thus many of these slaves were descended from the welsh, or brought from Ireland or Scotland. The Normans gradually made this class obsolete so some benefited from a crackdown on the peasantry.

overall, the relationship between lord and vassal was fundamentally altered. There was a deep ethnic division between the ruling and lower classes for the next 300 years. furthermore, there would be less social mobility, in Saxon times, theoretically a slave could buy their freedom, purchase their way into the nobility, prove himself worthy to serve as an ealdorman, marry into the royal house and be the father of the next king (of course it never really worked like this). in the new feudal order, status was strictly ascribed. Furthermore, things became worse for the lower classes, and the gap between rich and poor widened as the new lords removed privileges and differentiation between peasants. I would still hesitate to call this revolutionary however, as it was not exactly pioneering. It was not a drastic change in how society was organized, more the relationships within it and already in practice in most of Western Europe.