Sextuplet vs. Double Triplets

[fra ungdomsdagene]

Please, my teacher wants me to tap the rhythm of a complex exercise in the baritone C clef (actually I have to tap the rhythm while saying the name of the notes according to the french notation, and yes ... it is a total waste of time people in the rest of the world doesn't have to squander their time with) and in this exercise there's a series of sextuplets and double triplets and I can't tap them. My teacher isn't able to explain the difference to me and I can't do what I don't understand ... I could just be like most people and just parrot my teacher without understanding what we're talking about, but I can't be that superficial and I can't do something I don't thoroughly understand.
Can someone here please explain to me the difference between tapping a double-triplet and tapping a sextuplet?

Thanks to everyone
Fra

[gorbee natcase]

The sextuplets can be recorded and played back to your boredom at a phrase at a time and you can master them, treat it like washing the pots

[_tyro]

I think it's in the accents.  DUMdumdumDUMdumdum vs. DUMdumdumdumdumdum.   To me the sextuplet sounds bubblier. (Actually the accents shouldn't be very noticible, more for your mental reference. ) My problem isn't what the difference is, but rather when you should play which.  If you figure that out, please let us all know.