ATX and SFX are different form factors that do the same job. SFX is for small form factor cases, and has a different bolt pattern where it screws to the case than ATX. To get the Corsair SFX to physically mount to an ATX case that has an ATX motherboard, you will need an adapter. It will not bolt directly in.
https://www.corsair.com/us/en/Categories/Products/Accessories-Parts/PC-Components/Power-Supplies/SFX-to-ATX-PSU-Adapter-Bracket/p/CP-8920133