“Frum” means to follow the Torah to the best of your abilities. That’s all.
“Yeshivish” is a meaningless word and can mean a hundred different things to ten different people under ten different contexts. I think the best place it applies is as a comparative adjective: “That guy is more Yeshivish”, “That’s not as Yeshivish”, “What’s the less Yeshivishe rov say?”.