As a noun concept

is an understanding retained in the mind, from experience, reasoning and/or imagination; a generalization (generic, basic form), or abstraction (mental impression), of a particular set of instances or occurrences (specific, though different, recorded manifestations of the concept).

As a verb understand is

to be aware of the meaning of.

As nouns the difference between delusions and dementia

is that delusions is while dementia is (pathology) a progressive decline in cognitive function due to damage or disease in the brain beyond what might be expected from normal aging areas particularly affected include memory, attention, judgement, language and problem solving.

As nouns the difference between registration and license

is that registration is the act of signing up or registering for something while license is a legal document giving official permission to do something; a permit.

As a verb license is

the act of giving a formal (usually written) authorization.

As nouns the difference between hits and strikes

is that hits is plural of lang=en while strikes is plural of strike.

As verbs the difference between hits and strikes

is that hits is third-person singular of hit while strikes is third-person singular of strike.

As a determiner hits

is alternative form of lang=en.

As nouns the difference between arrow and hawkeye

is that arrow is a projectile consisting of a shaft, a point and a tail with stabilizing fins that is shot from a bow while hawkeye is a native or resident of the american state of iowa.

As a verb arrow

is to move swiftly and directly (like an arrow).

As a contraction arrow

is (obsolete).

As nouns the difference between immigrants and migrant

is that immigrants is plural of immigrant while migrant is a migratory bird or other animal.

As an adjective migrant is

migratory.

As adjectives the difference between bilineal and ambilineal

is that bilineal is tracing descent through both the patriline and the matriline while ambilineal is of or pertaining to both sides of a family.

As nouns the difference between struggle and struggling

is that struggle is strife, contention, great effort while struggling is the act of one who struggles.

As verbs the difference between struggle and struggling

is that struggle is to strive, to labour in difficulty, to fight (for or against), to contend while struggling is present participle of lang=en.

As a noun meekness

is the quality of being meek.

As an adverb cowardly is

in the manner of a coward.

As an adjective cowardly is

showing cowardice; lacking in courage; basely or weakly fearful.

As an adjective visceral

is of or relating to the viscera—internal organs of the body; splanchnic.

As a noun organ is

a largest part of an organism, composed of tissues that perform similar functions.

As a verb organ is

to supply with an organ or organs; to fit with organs.