Is the difference that now the basic search functionality actually works?
The previous standard GitHub search I found to be remarkably bad. I would be looking at some small public repo, search for an exact string match I know exists in the code, scope the search to that repo only, and still see zero results. Even copy-pasting a line of code from a file in the repo often resulted in zero matches.
It seems you still need to enable the feature. Click your user icon in the top right -> choose "Feature preview" in the dropdown -> enable the "New Code Search and Code View" feature.
The previous standard GitHub search I found to be remarkably bad. I would be looking at some small public repo, search for an exact string match I know exists in the code, scope the search to that repo only, and still see zero results. Even copy-pasting a line of code from a file in the repo often resulted in zero matches.