[bigwally]

Hipmunk only shows the flights that have tickets to sell through their partners.

Google has a lot more in terms of schedules.

[kn0thing]

Aye, mostly true. But Google doesn't tell you anything about whether the fares are available at all, or what they would cost—it's possible a flight's sold out or prohibitively expensive.

They also don't have mascot, or hotel search ;)

I'll leave it there.