formatting link
The upper one is an IR DirectFet. The lower one is a Fairchild leadless SO8.
IR claims 0.5 nH of source inductance, whereas the SO8, with three (wire bonded?) source leads, is probably more like 2. Given that some of these parts can switch over 100 amps in tennish ns, that could matter.
The IR package is sole-sourced, but several people make the other one.
The IR can be heatsunk from above, which could make for interesting packaging, super high power stuff that's still surface mount.