stretch vs stretch out

stretch is a noun but stretch out is not a noun.

Word	Noun	Adjective	Verb	Adverb
stretch	Yes	Yes	Yes	No
stretch out	No	No	Yes	No

As verbs, stretch out is a hyponym of stretch; that is, stretch out is a word with a more specific, narrower meaning than stretch:

Other hyponyms of stretch include spread-eagle, crane.

As verbs, stretch and stretch out are synonyms defined as:

As verbs, stretch and stretch out are synonyms defined as:

stretch and stretch out: extend or stretch out to a greater or the full length

Other synonyms of stretch include extend, unfold.

As verbs, stretch and stretch out are synonyms defined as:

stretch (noun)	stretch out (noun)
exercise designed to extend the limbs and muscles to their full extent
the act of physically reaching or thrusting out
extension to or beyond the ordinary limit
a straightaway section of a racetrack
the capacity for being stretched
a large and unbroken expanse or distance
an unbroken period of time during which you do something

stretch (adjective)	stretch out (adjective)
easily stretched
having an elongated seating area

stretch (verb)	stretch out (verb)
extend one's limbs or muscles, or the entire body	stretch (the neck) so as to see better
extend one's body or limbs	thrust or extend out
become longer by being stretched and pulled	extend one's body or limbs
make long or longer by pulling and stretching	extend or stretch out to a greater or the full length
extend the scope or meaning of; often unduly	lie down comfortably
increase in quantity or bulk by adding a cheaper substance
corrupt, debase, or make impure by adding a foreign or inferior substance; often by replacing valuable ingredients with inferior ones
pull in opposite directions
extend or stretch out to a greater or the full length
lie down comfortably
occupy a large, elongated area