Which is one way that the unicellular bacteria e. coli is different from a multicellular oak tree?

Given that E.coli is a Unicellular organism, this means it is single-celled as opposed to a multicellular organism like the oak tree which contain multiple cells.

As a unicellular organism, E.coli can be further defined as a bacteria, prokaryote (contain simple cells that lacks a nucleus or any type of organelles) and an heterotroph (dependent on other organism for their food consumption).