About a year ago I looked seriously at both of these models in addition to a few others. In general, the Trance is a bit higher spec than the Hawk Hill although both are excellent value aluminum bikes.
The Hawk Hill comes in 3 different specs (1, 2, and 3). The 1 is the lowest spec and the 3 is the highest. The specs mostly define the drivetrain (# of gears and configuration), suspension (shock and fork), wheels, brakes, and seatpost (the higher specs come with a dropper). I believe that the Hawk Hill 1 is $1599 list price in 2019 so that is probably what you are looking at. It does not have a dropper seatpost but does come with a Shimano XT 1x10 speed drivetrain. The wheels and brakes are entry level but adequate for lots of riding.
The Trance comes in a few different specs as well. However, with Giant, the 1 is the highest level spec with the best components - opposite of Marin. So depending on the spec of the Trance, it could be a significantly more valuable bike. For example, the 2018 Trance 2 listed for $2890 - almost twice the price of the Hawk Hill. The Trance 1 was even higher than that.
So on the surface, The Trance is probably a better spec bike than the Hawk Hill. However, there is definitely some advantages to buying a brand new bike as well so factor that in.
More importantly than all of this though - make sure that both of these bikes fit you properly. You can go to both Marin and Giant's websites and see these models (even the 2018 ones) and look at the suggested size charts relative to your height. The dealer(s) can also help with this. And by all means - ride them both. One may just feel "right".
So I ended up buying the Hawk Hill 1 and have since done a few upgrades to it over the past year and a few months (dropper, wheels, tires, pedals, grips, saddle...). I don't regret it at all - it is a great bike and is capable of much more than I am. I've owned quite a few Giants and love them but the Hawk Hill was the best option for me. I've been riding and enjoying the Hawk Hill for the last 14 months and am saving some $ for a new one in the next year or so - probably a SantaCruz Hightower, Ibis Ripley, or Niner Jet.