PvEs difficulty is determined by the majority of the highest players.
Example1: Everyone has a T2 ship equipped but at least 3 people have T3 ships or higher, the game will be T3/T4 PvE.
Example2: Everyone has T2 ships but 1 or 2 people have T3 ships or higher, the game is T2 PvE.
Some other information.
Note1: You rarely get T1 PvE if you’re in a squad.
Note2: Processing Rig only appears in T2.
Note3: Blackwood Shipyard is the only T1 mission.
Note4: Having a T1 ship equipped will always put you into Blackwood Shipyard.
T1 PvE gives you T1 military items, and T1 Experimental items.
T2 PvE gives you T2 military items, and T2 Experimental items.
T3/T4 PvE gives you T4 Military items, and T3 Experimental items.
As you can see, T3 Military items are completely skipped. The only way to obtain them is to do T3 PvP.
With that said, you can’t get T4 Experimental Items from PvE, T4 PvP is the only way to obtain them.
You can also determine what tier of PvE you are in right away.
T1: The initial wave on Blackwood Shipyard will be delayed by 10 seconds.
T2: There won’t be a delay in the initial wave on Blackwood Shipyard. You can also get another mission other than Blackwood Shipyard.
T3: Some Agents/Defenders aren’t marked with a Long Range Frigate symbol, instead they have an Engineering Frigate symbol.
(This information may be wrong, but it’s what I’ve gathered so far.)
[This information was gathered by the matchmaking system. Most of this information is null to Custom Battles.]
This information is null due to the recent changes.