Bury card means that it will reshow that card at a later time.
It is useful if you feel you do not want to review that card right now for some reason.
For example, I use it sometimes because I just reviewed a related card that would make the review too easy right now.
Suspend card means that it will not be shown again until you unsuspend it.
It is useful if you do not want to review that card at all or for an extended period of time.
For example, I use it when I realize I have a mistake in the card and I need to fix it before I can continue reviewing it.
Hope this helps.