The major qualities of Sativa medicinal strains include:

anti-anxiety
anti-depressant
treats chronic pain
increases focus and creativity
increases serotonin (a neurotransmitter involved in the regulation of learning, mood, sleep, anxiety and appetite)
for day time use
The major qualities of Indica medicinal strains include:

increased mental relaxation
muscle relaxation
decreases nausea
decreases acute pain
increases appetite
increases dopamine (a neurotransmitter that helps control the brain’s reward and pleasure centers)
for night time use
Hybrid:
Hybrid strains offer the best of both worlds. Many of the strains you’ll come across are hybrids, a crossbreeding of both sativa and indica strain or strains. In fact, because of how much cannabis has been bred, most strains you find will typically be a hybrid variety.