There are 3 different iterations of the game: 1 Suit, 2 Suit, and 4 Suit. 4 Suit Spider Solitaire is one of the most difficult solitaire varieties.
Unlike standard Solitaire (also called Klondike), Spider Solitaire uses an entire extra deck. It also uses a different tableau than you may be familiar with. Compared to your average game of Solitaire, Spider is often harder. Much harder.