Yeah, the "worker" conditions that followed were more like serfdom than chattel slavery. A serf's offspring is still tied to the land like their parents, so the practical difference probably wasn't that great, but it's still an important distinction.
Being forced to work 8-12 hours a day, but free to go about your business the rest of the time is a very different scenario to being owned and having your offspring becoming another persons property.
Chattel slavery goes way beyond forced labor - both are terrible, but not equally so.