difference, differ
違 centers on things not matching: a difference or divergence between two or more items. The core idea is that something is not the same as another, so it differs.
違 combines the movement radical 辶 with 韋, which likely contributes the sound and the idea of going against or diverging. The original sense is probably moving in a different direction.
The movement radical 辶 suggests walking, and 韋 looks like a guard tower or a walled enclosure. Picture two paths diverging around a walled area: one goes left, the other right, showing a clear difference.
For イ, imagine two paths that differ so much they look like the letter 'E' and its mirror image: 'E' -> イ, and the difference is easy to see.
to differ (from); to be different; to be distinct; to be unlike; to vary; to disagree (with)
difference; distinction; discrepancy
mistake; error; blunder
to be mistaken; to be incorrect; to be wrong
to make a mistake (in); to commit an error; to get wrong; to do incorrectly
violation; offense; offence; breach; transgression; infringement; contravention
misunderstanding; mistaken idea; wrong guess
illegal; illicit; unlawful
uncomfortable feeling; feeling out of place; sense of discomfort
madness; insanity; madman; lunatic; crazy person
difference; discrepancy; variation
unconstitutionality
out-of-place; inappropriate; sticking out like a sore thumb
mistaking one person for another; (case of) mistaken identity
difference; disagreement; conflict; clash; discrepancy; inconsistency
to mistake (for something or someone else); to be unable to recognize
cramp; sprain; crick; strain (muscle)
crossing without meeting (e.g. letters in the post, people on the road); going astray
to not match well (e.g. at the seams); to not mesh properly (of gears)
alternate; alternation
to be somewhat different (from before, from others, etc.)
sure; no mistaking it; for certain; without doubt
certain; sure; no doubt