Story points are relative measures (at least when you do it 'right'). What is so different from estimating things as 1/2/5/8 or S/M/L/XL? S (or 1) is roughly

Story points are relative measures (at least when you do it 'right'). What is so different from estimating things as 1/2/5/8 or S/M/L/XL? S (or 1) is roughly half as hard as M (or 2). M (or 2) is roughly half as hard as L (or 5). Notice how 2 is not exactly half of 5. Just roughly. And so forth. And the point is that you can't say how many S are exactly equivalent to how many Ls. Estimates tend to get less precise the larger they are. There's usually more uncertainty built into large estimates which means once you do the work it might be much faster or much slower because of things you didn't look at very closely when estimating. While small things are easier to have a complete overview of and the estimates are more accurate. A recent example from my work. There was something the team unanimously estimated as L. I knew it was an S. I knew the code though and they didn't. I let them put the L estimate on it. When the sprint started and I had some time I did the task myself and it really was an S in the end. But that's fine. They 'priced in' the uncertainty. If one if them had done it, it might very well have taken them longer because if not knowing the code as well.