In very general terms, there are exceptions to any generalization, I'm sure someone all argue some points below, but since you asked, from my own experience...
Sativas are typically higher THC content vs Indicas
They typically have lower CBD levels than Indicas (medical benefits and couch lock effect/high are CBD traits)
Sativas typically take longer to finish, for a new grower this is important as you'll have longer to keep the plant healthy before it's ready, more potential for problems to arise
Although they can grow tall/lanky under certain lighting, they can be manipulated with LST/SCROG etc to maintain a lower canopy and they tend to be easier to do that with than Indica's (probably not something a new grower wants/needs to deal with though)
Indicas typically finish faster
They typically grow straighter, not as bushy, less side shoots than sats
They are typically easier to grow and less finicky
They typically produce more weight (but not as high in THC)
Many strains have higher CBD (medicinal benefit, but also couch-lock effect)
In reality, it's more common to find blended strains or hybrids, where they're more dominant in sativa or indica, most of what's out there today is some form of hybrid.
IMO, go with an indica dominant strain until you get your feet wet and are comfortable with growing in general. There's a lot to deal with when you first start growing, particularly if growing indoor. Dealing with finicky strains, trying to maintain an even canopy, temps, humidity, broken equipment, and a host of other issues that can and will arise in your first grow(s), you want something easy to grow.
A lot of seed sites and review sites will grade the ease of grow for strains. Google is your friend, look for grow ratings, start easy and go from there. Good luck...
