What with both being boybands formed on the last series of the X Factor, it's probably not surprising that there's a spot of friendly rivalry, but even though they've now been released into the big bad world, Union J still reckon that they don't need to worry about District3 showing them up.
With the X Factor tour kicking off this week, all seven lads had a chat to Top of the Pops, but Union J aren't too worried about having to share the knicker throwing with the District3 lads.
Asked who gets the loudest screams, Jaymi said: "Us...maybe? It's a bit awkward, but yeah, I think so."
"I would say that our fans definitely scream the loudest! Everyone loves George - he's the little cutie in the band," JJ added.
But despite the banter, Josh isn't bothered either way as he's too busy fantasising about having hair with as large a fan club as Louis Tomlinson's.
He said: "We're not worrying aout District3. We want to be as successful as One Direction and The Wanted."
"I think we also have the most followers online.." George added, being the king of a subtle comment.
District3 aren't too bothered about all this chat though and are far too busy imagining what it would be like if they all held hands and sung S Club 7 hits.
"There's definitely no rivalry between us," Dan said. "We're more like a group of seven good friends.
"I think it's probably pretty equal, but then I haven't been to any of their gigs or anything," Greg said, ever the diplomat.
So what do you reckon - who would your rather chuck your knickers at?