Since you can exit, it's different.
Generally countries enter various nominally binding arrangements all the time, like ratifying UN treaties that are considered by courts to be part of national legislation etc. So "full sovereignty" in this sense is not so common.
(Also, EU law is drafted via a representational democracy system, so this use of power has an important quality of legitimacy that law handed down from the empire would lack)
> "The EU law has primacy over national law and all decisions by the European Court of Justice, including orders for interim measures, are binding on member states’ authorities and national courts,” chief spokesperson Eric Mamer said.
https://abcnews.go.com/International/wireStory/eu-court-pola...
Also, a Eurozone country can’t abandon with Euro without leaving the EU.
The context here is comparing the the EU with the British Empire.
Statements like “The EU law has primacy over national law” make it pretty clear what it means to be a member of the EU.