In the special arc of the Super Dragon Ball Heroes anime, Xeno Trunks turns into Super Saiyan God. In the other hand, it's unclear to me if Future Trunks of the same anime is capable to turn Super Saiyan Rage or only Super Saiyan 2. (I don't remember any episode of Future Trunks turning Super Saiyan Rage in Super Dragon Ball Heroes)
Which Trunks is stronger in Dragon Ball Heroes, future Trunks or Xeno Trunks?
Xeno-Trunks most probably is quite stronger than Future Trunks.
First, it should be noted that the Dragon Ball Heroes continuity (from which Xeno Trunks comes) is wildly inconsistent when it comes to scaling and power levels. All battles and transformations shown are created for the sake of game promotion and fan-service. So every feat must be taken with a grain of salt. Depending on whether you use the game, the manga or the anime as a basis for your comparisons, results can vary. I have chosen to rely on the DBH anime here since I am most familiar with that source.
The Super Saiyan 4 and Super Saiyan Blue are considered among fans to be roughly equals. This was implicitly chosen as true by the DBH anime : in episode 1, Xeno SSJ4 Goku and SSB Goku have a short skirmish, which concludes as a tie. Granted, their fight didn't last and they didn't go all out, but this can be interpreted as the anime deciding those forms are roughly equal.
Meanwhile, within the (canonical) Dragon Ball Super anime, we can see SSB Vegeto against Fused Zamasu. The saiyan warrior doesn't crush Zamasu, but still handles himself fairly well. On the other hand, Future Trunks is unceremoniously blown back, even with an enraged power boost. Future Trunks only slays Fused Zamasu after creating the Sword of Hope, which is basically a fortuitous Genkidama created around Future Trunks' sword. Trunks doesn't know that technique, and only used it by accident in extremely specific circumstances. We can conclude that Future Trunks is weaker than SSB Vegeto.
Now, what about Xeno Trunks ? The climax of the Super Dragon Ball Heroes anime involves Mechikabura, the Demon King, fighting both against Xeno SSJ4 Vegeto and Super Saiyan God Trunks. As we have previously established, Xeno SSJ4 Vegeto should be comparable to SSB Vegeto. Moreover, Xeno SSG Trunks is essential in sealing Mechikabura, as he deals a crucial blow to his torso and allows Xeno Vegeto to conclude the battle. We can infer from this battle that Xeno Trunks is stronger than Future Trunks, at least if Future Trunks doesn't have the Sword of Hope.
It should be noted, however, that SSG Xeno Trunks wielded the Key Sword against Mechikabura. That relic was supercharged by Demigra, Chronoa and Tokitoki, who all possess god-level ki and powers. If SSG Xeno Trunks didn't have the Key Sword at that time, he probably wouldn't have fared as well against Mechikabura.
In the end, we can only remember that anything related to Dragon Ball Heroes or Dragon Ball Xenoverse is fully non-canonical, and that their sense of scaling and relative power levels is fuzzy at best.
