The OnePlus 5 uses the same screen as the OnePlus 3T no, we dont mean the same specs, its the exact same panel. AIDA64 detects a Samsung S6E3FA5 panel on both devices.
This is a change from the original OnePlus 3, which had an FA3 panel. Its not entirely clear what the differences are between FA3 and FA5. Still, the OnePlus 5 has no hardware improvements over its predecessor, at least as far as screen is concerned.
OnePlus 5 uses a Samsung S6E3FA5 AMOLED display panel
Actually, our review shows a slightly lower maximum brightness and a slightly worse sunlight legibility for the OnePlus 5 compared to the 3T (which itself was a bit worse than the 3). What about DCI-P3? That seems to be a software thing (like how OnePlus enabled sRGB with an update).