Well primo is one of the mildest and maybe the most benign steroid out there while tren is one of the strongest and very harsh on you...
1. Mild lean gains with little to no sides.
2. Better gains but you wont feel as good (higher bp, anxiety etc).
Of course both are considering the dosages and everyone responds differently.
1-lean gain, good mood, good nuts revovery.
2-anxiety, sleep problem, night sweating, bp issue, hard nuts recovery but lean gain, strenght through the roof.