My high school gave an extra half point for honors and a whole point for AP classes*, but my experience was that regular classes were easier by _far_ more than that (at least in cases where all three levels were offered). I had disliked biology in middle school and separated from the "AP crowd" to take honors environmental science instead, and it felt at least two or three letter grades easier than the other AP sciences.

Of course the top tier students were likely to achieve an A regardless, so the more challenging courses would look better. For me though it probably would've been optimal to choose easier classes; admissions might not even be aware that a more difficult option was offered.

* If I recall correctly though, colleges were usually interested primarily in the unweighted GPA.