Klondike Solitaire comes in two versions: Draw 1 and Draw 3. The layout and rules are the same; the difference is how you go through the stock, and it changes the game more than you’d expect.
How the stock works
Draw 1: each tap turns over one card, so you can reach every card in the stock on every pass.
Draw 3: each tap turns over three cards, and only the top one can be played. You can only reach every third card, unless playing one shifts the order for the next pass.
Which is harder?
Draw 3 is clearly harder: cards you need can stay out of reach for a long time, so you win fewer deals. Draw 1 is more relaxed and wins more often, which makes it the better way to learn.
How scoring differs here
Going back through the stock costs 100 points in Draw 1. In Draw 3 the first three passes are free, then each one costs 20, because you need more passes to reach the same cards.
Which should you play?
Play Draw 1 if you want to win more and relax, and Draw 3 if you want a challenge that rewards careful play. You can switch in New game at any time, and your records are kept separately for each.