What is the difference between:
Context examples:
Either "for" or "until" would be idiomatic in both your examples. "Until" is slightly more pedantically correct, but a native speaker would understand either, and might use either (or the abbreviated "'til", dropping the "un-"). For most purposes, they mean the same thing in this context. The reason "until" is slightly more correct is that "tomorrow" is (in this context) acting as a time, rather than an object (for the arrival of which you might wait) or an event (for the occurrence of which you might wait).
In some slightly modified examples, "for" and "until" would still mean the same thing, but would need you to phrase the sentence differently:
However, as a side note, your examples probably do not mean what you think they mean. "You can better wait until tomorrow" means that you are better able (than something or someone else implied by context) to wait until tomorrow. Normally we would say "You had better wait until tomorrow".
to wait for means: to have high expectations about something or to be excited about something that will occur in a near future or more distant future. It is used in the negative even though the idea is positive.
- I can't wait for tomorrow. Meaning: my expectations about something good happening tomorrow are high.
Whereas:
- I can't wait until tomorrow. In standard English, this means: it is not possible for me to wait until that time, I need to do or say something today. But it is not related to one's expectations necessarily as wait for is.
Both your examples require "until" because "wait for tomorrow" in that context sounds unnatural.
"wait until tomorrow" indicates that the anticipated action can not happen before the designated time (tomorrow). For now, the person is forced to wait passively until a certain temporal condition is fulfilled, i.e. that today becomes tomorrow. The waiting period has a finite end. Then, the action or event can happen.
"wait for tomorrow" actually sounds a little strange to me, to be honest. But in general, waiting for something/someone does not necessarily constrain the waiting period to a specified time frame. If you wait for your friend, you don't actually know when they will turn up. You can wait for a bus, but it might never come. There is no finite end. In the case of "wait for tomorrow" there is a finite end, but as mentioned this phrase sounds somewhat unnatural since "wait for" tends to be used with more abstract time frames.
