I'm having trouble with my character when playing in unity, and when I build and run the game

Hey there guys, I'm running into a problem when I'm using Unity, where when I'm playing the game in unity my character appears to be walking finely along the platform with his feet just touching them (see attached picture) but when I test this game when I click build and run, the character appears to be floating on top of the blocks and no longer barely touches them. Anyone know what the problem is?

Playing it in the game view :

When I build and run the game

If anyone can help I'd greatly appreciate it!