Typical traits-
Sativa-
1)narrow leaf blades
2)tall plant
3)long flower time
4)fluffier buds
5)long internodes
6)'up' high
7)tropical origin
8)suitable for outdoor (tropical climate only)
Indica-
1)wide leaf blades
2)short plant
3)short flower time
4)denser buds
5)short internodes
6)stony high
7)temperate origin
8)suitable for indoor

These are just generalizations and hybrid strains available today may show combinations of these traits.