Stamina, body positioning, how straight you skate all matter.
20% difference in stamina can make a difference (probably).
If one guy has a better first step they'll have better positioning, any kind is huge for puck battles and races.
1 bad step left or right is also huge, some people don't notice it.
Stride style is probably the last thing that I would think is making a difference. It can make you look like you're going faster especially for the first few strides, and stick handling and pick ups can be different, but it shouldn't actually affect speed.
>> Also reach is probably really important. Not exactly sure how much it affects pick ups, you can probably test it yourself.