Demographics.
Ohio has a large white, working class & white, non-college educated population (both higher than the national average). Those groups normally vote Republican and have turned even further away from the Democratic Party since Obama's presidency and the rise of Trump. Also, the big cities of Ohio are just not enough to outweigh the rest of the state. Additionally, Ohio has only had 1 Democratic governor since 1991 (Ted Strickland who served only 1 term).
Florida is a tilt R state because of Cubans (especially older ones), Venezuelans and White retirees (who are largely conservative and racist). Obama was able to turn out enough Black voters and young people in '08 & '12 to win Florida. Florida is going to be won by Trump again (51-49% margin probably).