They only things that I expect to change are total premium, deductible, out of pocket expense, copays, and network. Otherwise, the coverage itself is dictated by the same law.
I can see right now that the BCBS gold HSA premium from my employer (total, including employer portion) is the same as the BCBS gold HSA available on healthcare.gov.
I used a hospital for a new baby birth. Because my plan was on-market, the provider doing delievery didn't accept it (Despite it being on the in-network list). So I got to be stuck with a ~13k bill. Was super cool.
This was back ~8 years ago, so perhaps it's all been sorted.. but I have such a bitter taste in my mouth after having to pay this out of pocket, I won't touch on-market plans with a 100 foot pole.