What is the difference between an "ante" and a "blind" in poker?
Ante and blinds are both forced bets.
Ante is a bet that everyone in the game must make in order to stay at the table. It forces there to always be at least some payout in the pot, increasing the relative value of playing a hand to folding.
Blinds are bets that only one or two players are forced to make, usually a small blind and a big blind, the small blind at half the big blind. They are bet by the two players after the dealer, and thus rotate around as the dealer rotates. The blinds start betting off; bidding starts with the player after the big blind, and players must call or raise the blind bet to stay in the game, otherwise they fold. It puts less in the pot than ante does, thus it does less to incentivize staying in the game, but it still puts enough in that it's worth it for some people to stay in as they do stand to win something, and the players who played the blinds stand to lose them if they simply fold.
Ante is given by all players before cards are dealt. It's effect is to make sure that everyone has some skin in the game, and that people don't instantly fold when dealt less than stellar cards.
Blinds are a different way of dividing up the ante so that only a few player are committed to the game before seeing their cards. They are generally split into big and small blinds. The big blind is the full 'ante' for the round. The small blind is a smaller sum. The blinds are bet before cards are dealt, but after seeing the initial cards, players can either fold, pay so that they have equaled the big blind, or place a higher bet.
When playing with an ante, all players have to give the same amount before they are allowed to see their cards. Thus, everyone has an equal stake in the current hand, and folding is less common in early betting rounds. (It's the "I already paid so I might as well stick around for another card" mentality.) Antes have the benefit of allowing players to sit out any hand (say, to go to the restroom or take a phone call) or even quite the game without any sense of unfairness.
Blinds are unequal forced bets usually imposed on two players per round. After seeing their cards, the remaining players have to call or raise to stay in the hand. Since there is initially an unequal stake in the hand, folding is common. (Why stay in if you haven't put anything in the pot and you have a lousy hand so far?) Also, savvy players can "over-raise" on the blind round to force everyone into folding, thus slowly building wealth by bleeding their opponents of the blinds. And with a blind system, if a player needs to leave the table for some reason, the fairness of the game becomes problematic, as they obviously can't leave when they are up for a blind, but leaving at another time would rob them of a "free" hand. Or does everyone wait however long it takes for that player to return?
(In case you can't tell, I consider blinds to be a blight on the noble game of poker. Antes are much more fair and superior to blinds in almost every way.)
Antes and blinds are both collected from players to "seed" the pot with a single bet. But they are collected in different ways.
An ante is collected from EACH player, but represents only a FRACTION of the basic bet. (The sum of the fractions, collected from each player, amount to about one bet.) As such, everyone "pays the same," and no one is at a disadvantage versus anyone else.
A (big) blind is a basic bet collected from ONE player. (A small blind, half the basic bet is sometimes collected from a second player.) They are called "blinds" because these players have to bet "blind" before receiving their cards. The others can look at their cards before deciding to call, raise, or fold to this "forced" bet.
The (big) "blind" bettor is thus placed at a disadvantage, but can reasonably stay in with "any two cards" (if not raised), since s/he bet before receiving cards. This adds an element of randomness to the game. (The small blind can play "loose" for only half a bet.)