In transitive terms the difference between jar and crash

is that jar is to shock or surprise while crash is to severely damage or destroy something by causing it to collide with something else.

As an initialism JAR

is initialism of Java ARchive|lang=en.

As an adjective crash is

quick, fast, intensive.

As verbs the difference between maintain and guarantee

is that maintain is to support (someone), to back up or assist (someone) in an action while guarantee is to assure that something will get done right.

As a noun guarantee is

anything that assures a certain outcome.

Spiral is a related term of eye.

As a noun spiral

is spiral.

As a proper noun eye is

(uk|colloquial) the comedic magazine.

Wail is a related term of reverberation.

As nouns the difference between wail and reverberation

is that wail is a prolonged cry, usually high-pitched, especially as of grief or anguish while reverberation is reverberation.

As a verb wail

is to cry out, as in sorrow or anguish or wail can be (obsolete) to choose; to select.

Progeny is a related term of increase.

As nouns the difference between progeny and increase

is that progeny is (uncountable) offspring or descendants while increase is an amount by which a quantity is increased.

As a verb increase is

(of a quantity) to become larger.

Fabricate is a related term of dissemble.

In lang=en terms the difference between fabricate and dissemble

is that fabricate is to invent and form; to forge; to devise falsely; as, to fabricate a lie or story while dissemble is to falsely hide one's opinions or feelings.

As verbs the difference between fabricate and dissemble

is that fabricate is to form into a whole by uniting its parts; to frame; to construct; to build; as, to fabricate a bridge or ship while dissemble is to disguise or conceal something.

As verbs the difference between made and developed

is that made is past tense of make while developed is past tense of develop.

As a noun made

is a maggot or grub.

As an adjective developed is

not primitive; not third world.

Unstable is a synonym of unsafe.

As adjectives the difference between unsafe and unstable

is that unsafe is not safe; dangerous while unstable is having a strong tendency to change.

Length is a related term of portion.

As nouns the difference between length and portion

is that length is the distance measured along the longest dimension of an object while portion is portion.

As a verb length

is (obsolete) to lengthen.

As adjectives the difference between admirable and impeccable

is that admirable is deserving of the highest esteem or admiration while impeccable is perfect, without faults, flaws or errors.