set vs activity

set and activity both are nouns.

Word	Noun	Adjective	Verb	Adverb
set	Yes	Yes	Yes	No
activity	Yes	No	No	No

As nouns, activity is a hypernym of set; that is, activity is a word with a broader meaning than set:

set: the process of becoming hard or solid by cooling or drying or crystallization
activity: a process existing in or produced by nature (rather than by the intent of human beings)

Other hypernyms of set include action, natural action, natural process.

set (noun)	activity (noun)
several exercises intended to be done in series	any specific behavior
the act of putting something in position	the trait of being active; moving or acting rapidly and energetically
representation consisting of the scenery and other properties used to identify the location of a dramatic production	an organic process that takes place in the body
any electronic equipment that receives or transmits radio or tv signals	a process existing in or produced by nature (rather than by the intent of human beings)
(psychology) being temporarily ready to respond in a particular way	the state of being active
a relatively permanent inclination to react in a particular way	(chemistry) the capacity of a substance to take part in a chemical reaction
the descent of a heavenly body below the horizon
a group of things of the same kind that belong together and are so used
an unofficial association of people or groups
(mathematics) an abstract collection of numbers or symbols
the process of becoming hard or solid by cooling or drying or crystallization
a unit of play in tennis or squash

set (adjective)	activity (adjective)
set down according to a plan
being below the horizon
converted to solid form (as concrete)
fixed and unmoving
(usually followed by `to' or `for') on the point of or strongly disposed
situated in a particular spot or position
determined or decided upon as by an authority

set (verb)	activity (verb)
arrange attractively
produce fruit
alter or regulate so as to achieve accuracy or conform to a standard
put into a certain state; cause to be in a certain state
set to a certain position or cause to operate correctly
equip with sails or masts
become gelatinous
make ready or suitable or equip in advance for a particular purpose or for some use, event, etc
get ready for a particular purpose or event
fix conclusively or authoritatively
estimate
decide upon or fix definitely
establish as the highest level or best performance
urge to attack someone
put into a certain place or abstract location
fix in a border
give a fine, sharp edge to a knife or razor
insert (a nail or screw below the surface, as into a countersink)
put or set (seeds, seedlings, or plants) into the ground
put into a position that will restore a normal state
adapt for performance in a different way
locate
set in type
apply or start
disappear beyond the horizon