I haven't noticed much, managing my own domains and some low traffic third parties. I have experience with namecheap, 101domains, gandi, godaddy, and others I can't remember from the top of my head. The most tangible for me is the web interface they give you - I like gandi's the most, and there are some shitty providers that don't even have one. Otherwise they are similar, they reserve the domain for you, let you set it up and provide nameservers so that you don't have to host those. Another difference is how much their website, and their renewal flow makes you hate life with all the dark patterns they employ. Godaddy and 101 were quite horrible in this regard, I really needed to double-check before paying that they haven't slipped in a value-add that I don't need, but would cost me nevertheless. Again, gandi is one of the better ones in this regard too.

Gandi also has a nice API to manage the domains. I use that with a simple shell script to have my own dynamic DNS.

So if your usage is as limited as mine, no major differences really.