From the Super Mario Wiki
Snufits are floating, Boo-like enemies similar to Snifits. They first appear in Hazy Maze Cave, specifically in the Metal Cavern, during the events of Super Mario 64 and Super Mario 64 DS. When Mario comes to close to one, it will shoot a burst of small balls out of its mouth like a Snifit, although this action is preceded by the Snufit briefly swelling up like a balloon before firing in the original Super Mario 64. Snufits can be defeated by jumping on them. In their original appearance, Snufits had white masks like Shy Guys, while in the Super Mario 64 DS remake, their design was more faithful to the black-masked Snifits, save for the lack of legs and ability to float, which is the same in both versions of the game.
They later make an appearance in Mario Party 2 on the Space Land board as the Snufit Police, but they are referred to as Snifits in some copies of the game. They can fire small projectiles similar to rocks.
Although their English name in Super Mario 64 is similar to but different from that of Snifits, their Japanese name is identical. Some versions of the English release of Mario Party 2 (including the Virtual Console release) also refer to them as Snifits in addition to other versions which use the name "Snufit".