useful

As adjectives the difference between necessary and useful

is that necessary is needed, required while useful is having a practical or beneficial use.

As a noun necessary

is bathroom, toilet, loo.

As an adjective useful

is having a practical or beneficial use.

As a noun advantage is

any condition, circumstance, opportunity or means, particularly favorable to success, or to any desired end.

As a verb advantage is

to provide (someone) with an advantage, to give an edge to.

As adjectives the difference between useful and reasonable

is that useful is having a practical or beneficial use while reasonable is having the faculty of reason; endued with reason; rational.

As adjectives the difference between available and useful

is that available is such as one may avail one’s self of; capable of being used for the accomplishment of a purpose while useful is having a practical or beneficial use.

As adjectives the difference between desirable and useful

is that desirable is suitable, worthy to be desired while useful is having a practical or beneficial use.

As a noun desirable

is a thing that people want; something that is desirable.

Commodious is a synonym of useful.

As adjectives the difference between commodious and useful

is that commodious is spacious and convenient; roomy and comfortable while useful is having a practical or beneficial use.

As adjectives the difference between essential and useful

is that essential is necessary while useful is having a practical or beneficial use.

As a noun essential

is a necessary ingredient.

As adjectives the difference between useful and sensible

is that useful is having a practical or beneficial use while sensible is perceptible by the senses.

As a noun sensible is

sensation; sensibility.

As adjectives the difference between useful and reliable

is that useful is having a practical or beneficial use while reliable is suitable]] or fit to be [[rely on|relied on; worthy of dependence or reliance; trustworthy.

As a noun reliable is

something or someone or dependable.

Germane is a related term of useful.

As a noun germane

is german, member of germanic tribe.

As an adjective useful is

having a practical or beneficial use.