access vs back door

access and back door both are nouns.

Word	Noun	Adjective	Verb	Adverb
access	Yes	No	Yes	No
back door	Yes	No	No	No

As nouns, back door is a hyponym of access; that is, back door is a word with a more specific, narrower meaning than access:

Other hyponyms of access include backdoor.

As nouns, back door is a hyponym of access; that is, back door is a word with a more specific, narrower meaning than access:

access: a code (a series of characters or digits) that must be entered in some way (typed or dialed or spoken) to get the use of something (a telephone line or a computer or a local area network etc.)
back door: an undocumented way to get access to a computer system or the data it contains

Other hyponyms of access include backdoor.

access (noun)	back door (noun)
the act of approaching or entering	a secret or underhand means of access (to a place or a position)
a way of entering or leaving	an entrance at the rear of a building
(computer science) the operation of reading or writing stored information	an undocumented way to get access to a computer system or the data it contains
the right to enter
the right to obtain or make use of or take advantage of something (as services or membership)
a code (a series of characters or digits) that must be entered in some way (typed or dialed or spoken) to get the use of something (a telephone line or a computer or a local area network etc.)

access (verb)	back door (verb)
reach or gain access to
obtain or retrieve from a storage device; as of information on a computer