Normal Sit and go have a Stack depth of 50 BB + and you have a table size of 8 - 9 players per table at start.
They also have a fixed pay-out structure (1., 2. , and 3. get paid for 9 player sit and gos).
They are much better for beginners and learning players.
Sadly, only a few sites offer these games since they have a so called solved strategy.
Blast (Spin and Gold, Spins a bit better starting stack of at least 15 bb) are very shallow stacked,
from 7 to 15 BB depending on the multiplier for pay-outs (2x, 3x and so on) you get.
Mostly only 1. gets paid only on higher multipliers 2. and 3. are paid.
They are very fast, and it is an absolute luck
gambling format.
Variance is ultra here.
Not for beginners.