Stalemate: the player to move has no legal move and is not in check (Art. 5.2.1); Dead position: neither player can possibly checkmate (Art. 5.2.2); Agreement: permitted once each player has made at least one move (Art. 5.2.3)
Why people argue about this
People often assume that a stalemate is simply when a player can't make a move, forgetting that they also have to be not in check for it to count as a draw under FIDE rules. The confusion arises because players sometimes think they're entitled to declare a draw whenever their opponent has no legal moves, which isn't always the case and doesn't align with Art. 5.2.1.
