These are in reference to abyssal filaments. They are different tiers of difficulty with T0 being the easiest and T6 being the hardest and most rewarding. T4 Gila means that this Gila fit is capable of T4 abyss assuming max skills.
Yep, the same terminology is used for different things.
T1 (basic) and T2 (upgraded) modules for fitting ships.
T1 (basic), T2 (specialised) and T3 (flexible) ships.
T0-T5 levels (tiers) within Abyssal space.
So, the idea of a T2 fitted T1 cruiser in T0 abyssal space is a thing that means something to us old fogies.
There is very little correlation between the three.
Though if you see a T1 fitted T2 ship you know you are dealing with someone who is a little unbalanced.
I run a T2/deadspace fitted T2 HAC in T3 abysses. It’s plain sailing.
Almost Sacrilegious.