One of the bigger differences is speed, someone that has used a specific framework a lot will likely be much faster in creating new stuff in it than someone tha

One of the bigger differences is speed, someone that has used a specific framework a lot will likely be much faster in creating new stuff in it than someone that never used it. A lot of typical tasks will fall into the "I've done that before" category, which does speed up things a lot. For me the most time-consuming part when working with entirely new technology is figuring out how to do certain parts. And for some of them I will initially miss better approaches because I didn't know about them. The other part that is time-consuming are unexpected or complex behaviours that lead to bugs or unexpected behaviour. Every framework has a bunch of stuff that tends to surprise new developers, if you've already worked with it those parts will likely be familiar.