The differences in the two climate's environment!

Vegetation!

The vegetation of Boreal regions is dominated by vast forests of coniferous trees.

Desert vegetation is very scarce, because water is in very short supply!

Wildlife!

There are a wealth of different animal species in the Boreal Forests.

Deserts actually have a high biodiversity!

Soil!

Boreal soil:
The soil is covered usually by permafrost or rocks and underneath that there is clay like dirt.

Deserts:
It is totally sand though there may be arable soil somewhere below those deserts.