Pretty much no difference except color.
Ever since Cubase SX I’ve always said that we should have our effects rack back like we did in Cubase VST and effects RETURNS created for each effect added with the output of the effect hard-wired to the input of the return rather than inserted on a faux group. Every thing else about the FX track could remain the same including the ability to insert more items onto the return.
And for those of you who like to insert FX onto a group and use it as a return, you still can.
Here’s a lively debate on the topic.