Power hacksaws of similar capacity have a smaller footprint. While smaller, hacksaws tend to be heavier.
All else equal bandsaws cut faster.
Hacksaws are often said to be slower than a bandsaw, and apples to apples this is true. However since hacksaws tend to be smaller, a hacksaw of a similar footprint may actually outperform a bandsaw. This is particularly true if comparing a heavy commercial hacksaw to a cheaper light duty bandsaw.
Hacksaws aledgedly cut straighter than bandsaws, but blade size is a big factor here. With the smaller size saws hobbyists tend to prefer hacksaws tend to allow the use of bigger 3/4" to 1-1/4" blades vs 1/2". On a larger bandsaw with 1"+ blades this may be less of a factor.
Since many consider hacksaws obsolete, you can often find really good deals on them.