Perceive refers to the capacity of perception through your senses. You can perceive something through one or more of your senses, that is seeing, smelling, touching, hearing or tasting.
But to perceive something doesn't necessarily imply that you understand or realize it:
I can perceive something in the sky but I can't realize what it is.
However, there are instances when you may assimilate the perception to an understanding, for example definition #2 from American Heritage Dictinary of the English Language:
- To achieve understanding of; apprehend: Einstein perceived that energy and matter are equivalent.
There are at least two ways these terms can be used:
1) They can be used to indicate assent:
For example:
We need some more eggs to make the soufflé. Can you go buy some?
Alright. (or, Okay.)
2) They can be used to indicate that the quality of something is "satisfactory but not exceptionally or especially good":
For example:
How was the movie last night?
It was okay. (or, It was alright)
In these two contexts, I find these terms pretty much interchangeable. In the first, you agree, but without any particular eagerness. In the second, they both convey about the same sense of enthusiasm (or apathy).
I will offer an opinion that differs slightly from Mowzer's: I think they are both somewhat general and informal terms. If for some reason more formality, politeness, or precision is called for, I would recommend using different words altogether. For example:
Judge: I'll need you to approach the bench and take the oath.
My response: Yes, your honor. (not, "Alright" or, "Okay")
English Professor: What did you think of the Faulkner story you read this weekend?
My response: It has a good message, but it's a little dry. (not, "It's alright" or, "It's okay")
Girlfriend's mother: We need some more eggs to make the soufflé. Can you go buy some?
My Response: I'd be glad to. (not, "Alright" or, "Okay")
I think your question is a fair one, and your analogy is a good one. But, in this case, I think the two words are much more interchangeable than, say, broke and bankrupt.
Best Answer
This is the most natural sounding phrase. There is only one thing that is bad about it. You state the bad thing, and reiterate that it stands alone as being a fault.
Everything means all of the things of a group - it refers to the collection, and the collection normally has more than one item within it. While it isn't horribly wrong, and would be understood, I would not use this.
Every thing highlights each of the things as it's own entity, rather than as a collective. Imagine if I said Make sure every thing is put away. I am acknowledging that different things have different repositories, and asking for the listener to exercise care that each item is treated with care. 999 of the 1000 items being stowed, is NOT every thing.
Contrast with Make sure everything is put away. Now I am not focusing on these objects as separate things. As a collection, I want them put where they go. And if I put away 48 of the 50 things that were out, I might be OK saying I put away everything.
I can picture a circumstance where I would use every thing in your phrase.
That is everything I have to say about this.