.......................... comparing a god against a mortal?
at the age of 15 tenchi got already 3 wings then 2 years after on ova 3 thanks to the destruction of universe he evolve into 6 wings.
Then after 15 years. The time of iseka with Kenchi having 1 wing. -_- -_-
It's hard to compare thanks to the super insanely large gap. Kenchi more likely had the fire power of about 3rd generation Jurai royal Ship but Tenchi with the age of 15 can compare on a 1st generation with 3 wings. He already surpass the first generation with a huge gap already.
Plus Kenchi is having a nice time. With a school and a whole school of harem at his age while Tenchi is fighting in space. Even though they had the same age at that time. Just from experience and raw power. The different is too big.