Just wondering. Poll to follow. Also, please provide what you think the difference is, if any.
The difference in both pronunciation and emphasis is very obvious to me.
WEAK’nd
weekEND
Yes, there’s a very distinct difference. “Weekend” is pronounced almost as if it were two separate words, while “weakened” is pronounced more like a single word with less stress on the second syllable.
Another difference is that the last “e” in “weekend” is pronounced like “eh” as opposed to the “uh” sound in “weakened.”
There’s no difference in the first syllable (“weak”=“week”), but in “weakened”, the vowels aren’t pronounced in the 2nd syllable (could be “weaknd”). In “weekend”, the ‘e’ in the 2nd syllable is distinctly pronounced.
ETA: what Leaffan said, much more succinctly.
Definitely different in my experience. The difference is usually distinct, sometimes subtle, but always detectable.
Weakened: WEEK-ənd (WEEKind), with the vowel in the second syllable swallowed, almost nonexistent
Weekend: WEEK-end, with the vowel in the second syllable clearly a “short e”
To me, the difference is pretty subtle, to the point they could almost be said interchangeably. I live in the Northeastern U.S.
Northeast and New England, too. Very obvious in the way others have pointed out. Weekend almost sounds like two words with heavy emphasis on the “end”, weakened is clearly one word with the end sounding more like “ind”.
The biggest difference in my dialect (Chicago) is the vowel sound in the second syllable. Not having access to the phonetic alphabet, the best I can describe it is that Weekend has the same vowel sound as “pen”, while Weakened has the same vowel sound as “pin”. (Of course, this won’t help those of you for whom pen and pin are homophones.) “Weakened” actually sounds almost exactly like “weaken”, with a teeny tiny “d” at the end. The second vowel in “weekend” requires the mouth to be more open and the tongue down further.
The difference is slight, and if you said one for the other at conversational speed, no one would notice, though.
Weakened = week-und - u as in “under”
Weekend - week-ind i as in “in”
I’m with Evil Captor.
Also the stresses are different, so:
WEAK-und
vs
week-IND
although the stress difference may have something to do with where the words usually fall in speech, rather than an intrinsic difference in the words just by themselves. I ***think ***of them that way because that’s how I say them most often, but I don’t know if it would sound as distinct if I just said the words off of a list.
Waitaminnit. Are some of you putting the stress on the last syllable in ‘weekend’? 
In “weaken” or “weakened,” the second syllable has a schwa, and the accent is definitely on the first syllable.
In “weekend,” the second syllable has a short e (just like in the word “end”). The accent is still on the first syllable, but the second syllable has more stress than it does in “weakened.”
I have heard people stress the first syllable in “weekend,” and might even do it myself occasionally, but I think it is more common to stress the last. In either case, it sounds distinctly different from “weakened.”
That’s a British thing I think.
This thread would be a lot more useful/interesting if people INCLUDED THEIR LOCATIONS.
Do you have an example? It’s certainly the first syllable that’s stressed in the Loverboy song “Working for the Weekend”.
I’d say both syllables in “weekend” are more or less equally stressed, so perhaps folks are saying that the second syllable is stressed compared to “weakened,” in which the stress on the first is heavy and obvious.
weakened = WEE-kinned (or perhaps more accurately WEE-knd)
weekend = week-end (I rarely hear WEEK-end and never week-END)
(Chicago)
That’s a typical Central/Western Canadian accent, such as I have. I wonder about some of the others…