I played around with Safari, Chrome, Terminal, MacVim and iTerm. It works for Safari, Chrome and Terminal, but moving MacVim and iTerm to the left doesn't tile

I played around with Safari, Chrome, Terminal, MacVim and iTerm. It works for Safari, Chrome and Terminal, but moving MacVim and iTerm to the left doesn't tile them, they just occupy the left of the screen entirely. MacVim and iTerm also are slightly wider when at the left and slightly narrower when at the right (their left + right width fills the entire screen). Anyone else experience this too?