The difference between Grass and Herb

Grass as a noun (countable, uncountable):

Any plant of the family Poaceae, characterized by leaves that arise from nodes in the stem and leaf bases that wrap around the stem, especially those grown as ground cover rather than for grain.

Grass as a noun (countable):

Various plants not in family Poaceae that resemble grasses.

Grass as a noun (uncountable):

A lawn.

Grass as a noun (uncountable, slang):

Marijuana.

Grass as a noun (countable, Britain, slang):

An informer, police informer; one who betrays a group (of criminals, etc) to the authorities.

Grass as a noun (uncountable, physics):

Sharp, closely spaced discontinuities in the trace of a cathode-ray tube, produced by random interference.

Grass as a noun (uncountable, slang):

Noise on an A-scope or similar type of radar display.

Grass as a noun:

The season of fresh grass; spring.

Grass as a noun (obsolete, figurative):

That which is transitory.

Grass as a noun (countable, folk etymology):

Asparagus.

Grass as a verb (transitive):

To lay out on the grass; to knock down (an opponent etc.).

Grass as a verb (transitive, or, intransitive, slang):

To act as a grass or informer, to betray; to report on (criminals etc) to the authorities.

Grass as a verb (transitive):

To cover with grass or with turf.

Grass as a verb (transitive):

To expose, as flax, on the grass for bleaching, etc.

Grass as a verb (transitive):

To bring to the grass or ground; to land.

Herb as a noun (countable):

Any green, leafy plant, or parts thereof, used to flavour or season food.

Herb as a noun (countable):

A plant whose roots, leaves or seeds, etc. are used in medicine.

Herb as a noun (uncountable, slang, euphemistic):

Marijuana.

Herb as a noun (countable, botany):

A plant whose stem is not woody and does not persist beyond each growing season

Herb as a noun (uncountable, obsolete):

Grass; herbage.