Nah episome is just a type of plasmid. Theres 2 types of plasmids: episomes(integrating plasmids) and non-integrating plasmids.
Non-integrating plasmids are the common ones I think..they don't touch the bacteria's chromosome
And episomes are the ones that mix into the bacteria's chromosome
Right but just to point out episomes don't have to mix into the chromosome but have the Capability to do so.