As nouns the difference between vinyls and olefins

is that vinyls is plural of lang=en while olefins is plural of lang=en.

As a noun book

is book.

As a verb appoint is

(obsolete|transitive) to fix with power or firmness; to establish; to mark out.

As adjectives the difference between despondent and optimistic

is that despondent is in low spirits from loss of hope or courage while optimistic is expecting the best in all possible ways.

As proper nouns the difference between guwahati and dispur

is that guwahati is a large city in India, in the state of Assam while Dispur is state capital of Assam (India).

As adjectives the difference between reliable and favourable

is that reliable is suitable]] or fit to be [[rely on|relied on; worthy of dependence or reliance; trustworthy while favourable is pleasing, encouraging or approving.

As a noun reliable

is something or someone or dependable.

As verbs the difference between facilitate and bridging

is that facilitate is to make easy or easier while bridging is .

As an adjective bridging is

that acts as a bridge (in many contexts).

As a noun bridging is

(architecture) the system of bracing used between floor or other timbers to distribute the weight.

As nouns the difference between chariot and coach

is that chariot is a two-wheeled, horse-drawn vehicle, used in bronze age and early iron age warfare while coach is a wheeled vehicle, generally drawn by horse power.

As a verb coach is

(sports) to train.

As an adjective arid

is very dry.

As a verb desiccate is

to dry.

As a proper noun mercy

is , one of the less common puritan virtue names.

As an adjective grateful is

showing appreciation, being thankful.

As an adjective necessary

is needed, required.

As a noun necessary

is (archaic|british) bathroom, toilet, loo.

As an adverb completely is

(manner) in a complete manner; fully; totally; utterly.