I would venture to say they are different for sure, but there is a market for both.
I am still in the process of learning WP as well, but I have some basic sites done in it. It would have been easier for me to learn it if I had hand coded 1-2 sites in html / css first, then moved them to WP. It wouldn’t have been so confusing.
I think it would be good to learn php in your case as well.
To me the differences are php is easy to pick up, but I know due to flexibility it’s great to use for small / medium size sites.