compare to / compare with

Hi. What's the difference between compare to and compare with? Thanks.

I would say there's little or no difference, and the two are interchangeable in most contexts.

However, when using an "each other" construction, I think that compare with sounds a little better -- it emphasizes that the comparison is "in both directions." So, in the sentence:

"How does Russian rye bread compare __ American rye bread?"

...you can use either "to" or "with." But in the sentence:

"How do Russian and American rye breads compare __ each other?"

...I would generally prefer "with," although "to" is not incorrect from a grammar standpoint.

P.S. To answer that question, American rye bread is rarely 100% rye, and sometimes may be as much as 50% wheat, so it's softer and much less sour than Russian rye bread. (However, which one is "better" depends on whether you're eating it с клубничным джемом, or с горчицей и ветчиной, IMHO.)

The two expressions are interchangeable for the most part, although there are a few situations where one might sound better than the other...

He compares himself to other people too often ("compares to" seems to infer a greater contrast between the things being compared)
He compared dry cereal with hot cereal and decided he liked dry cereal better ("compare with" seems to infer less contrast)

There is one use of "compared to ..." as a retort, or exasperation, or something. I don't recall hearing anyone use 'with' for that use. In:
"Compared to what?!"

This is used in a song. "Trying to make it real - compared to what?"

Generally, use "to" when comparing two things that are essentially different, and use "with" when comparing things that are essentially the same.

For example, "It's like comparing apples to oranges." These two things are essentially different from each other, and so we use "to". Or taking Deborski's example from above, "He compared dry cereal with hot cereal". We use "with" because both items are essentially cereal, if not but for a minor qualitative difference (temperature).

However, it's not necessarily the state of the object that you're carrying that matters as much as the qualities/quantities you're trying to compare. For instance before it was "apples to oranges", but it would be more appropriate to say "He's comparing the shape of an apple with the shape of an orange." because the shapes are extremely similar, thus "with" is more suitable.