I was casting around for a good translation of Oneg, ענג,
when all of a sudden it struck me...
I should have realized this years ago, and maybe you did,
but it only hit me this past Friday:
Oneg and enjoy are the same word!
The ע, נ, ג of Oneg are the same as the E, N, J of Enjoy!
Which captures precisely the difference between happiness as in Simchas Yom Tov, and enjoyment, as in Oneg Shabbos!
And it took me this long to realize it! Let me know in the comments if for you this was a davar pashut or a chiddush.