Answering "craps buy vs place" starts with the shape of one round. Craps is played with two dice and a crowded layout, and almost all of it makes sense once that shape is clear. One player throws, everyone at the table may bet, and the round runs from the first throw to the moment the table either repeats a number or rolls a seven. The bets printed around the layout are answers to what can happen within that sequence.
The rest of the layout holds wagers that settle differently. The field is a single roll bet on a group of totals. Place bets sit on a chosen number and stand until it arrives or a seven does. Hardways ask for a pair — two threes for a hard six — before either a seven or the easy version of that number. The middle holds one roll propositions, called out to the stickman rather than placed by hand, and the crew is a boxman over the bank, two dealers and that stickman.
The round opens with the come out roll, thrown with the marker sitting off to one side. A seven or an eleven wins immediately for the pass line, the bet most players make first. A two, a three or a twelve is craps and loses it. Any other total — four, five, six, eight, nine or ten — becomes the point, and the marker is turned over onto that number to show the round is under way and that the next throws answer to it.
Once a point is set the shooter keeps throwing until one of two things happens. The point repeating pays the pass line and starts a fresh round with the same shooter. A seven arriving first is a seven out: the pass line loses, the dice move on to the next player, and the marker goes back over. The don't pass line is the mirror of all this, winning where the pass line loses, except that a twelve on the come out is a push rather than a win.
A field bet covers a group of totals and is decided on the very next roll, winning or losing in that single throw.
Don't pass wins where the pass line loses, except that a twelve on the come out is a push instead of a win.
A place bet on a chosen number stands until that number is rolled or a seven arrives, whichever comes first.
A boxman supervises the bank, two dealers handle bets around the layout, and a stickman moves the dice and takes calls on the one roll propositions in the middle.