More often I see people use the words soil and dirt interchangeably. Is this correct? I often held that dirt as generic. Dictionary also suggests a generic definition: anything that makes something unclean (including mud or soil) and the use of dirt in place of soil is a US phenomenon.
Is it a standard usage?
Overlapping meaning, but different in connotation.
Soil is the stuff outside that you grow plants in. It is "natural" and "good"
Dirt is stuff on something that is staining or messy. It is something that should be cleaned. So if you have soil on your clothes, you would call that "dirt". But you could also a food stain, or house-dust "dirt".
In casual speech, particularly in American English, though I've heard it used by old people in London too, dirt is used to mean "soil". Sometimes with a negative meaning.
There are lots of figurative uses of "dirt" in which it can mean "rumour or gossip"
