Which one? Vandal or Phantom? Pros and cons to both?

I just started playing. I get more headshots with the phantom but the vandal does more damage right? I struggle with the spray on the vandal. Tips? Tips for newbies? Especially new pc gamer who hasn't played anything before?

My boyfriend is imm3 and makes everything look so easy, but ITS NOT. He forgets the basics which I struggle with: setting my sens, picking a gun, remembering my abilities, remembering what button, where the button on the keyboard is etc. Any tips for those things as well? I've never played a videogame so any advice helps.