What is the difference between "vice" and "deputy"?

I know 'vice' and 'deputy' both mean "next in rank". In Merriam-Webster, we have these definitions:

vice:

one that takes the place of vice-chancellor

In comparison to:

deputy:

a person appointed as a substitute with power to act

a second in command or assistant who usually takes charge when his or her superior is absent; specifically : deputy sheriff

So the two have clearly similar meanings, suggesting a person who does not normally carry the full responsibility of a given position, but who can perform those same duties as required or directed to. Also, there are towns with Vice Mayors, and other towns with Deputy Mayors.

Can anyone tell their difference, such as usage or anything else? Are they completely interchangeable and merely a matter of of a particular organization's preferences?

Solution 1:

Vice

Refers to the one second in command, next in authority to another person. It's used for people who are one step away to the highest authority. Their job is different from the higher person's. They're not authorized to act on behalf of the boss, unless they're told to do so.

Usually, a vice is someone, a person (maybe two persons, but not more). Not a group of people. Example:

vice president, vice admiral, vice chairman

Meanwhile:

Deputy

Refers to the one(s) appointed to act for another person (not necessarily next in command), to take their place on their behalf. What they do is subset to the higher person's authority. Usually, a person can have a number of deputies. Example:

Deputy manager, deputy sheriff.

The word deputy is also commonly used in organizations. At where I work, we have six deputies (not six vices).

Solution 2:

Vice is someone who is second highest in position and can take up number one position in case of sudden demise of the person occupying number one position, without holding any fresh election. For example Vice President of USA, Vice President of Union of India can take over as Presidents in case of sudden demise, removal or resignation of Presidents. Whereas Deputies are meant only to assist the people in number one position and cannot take over number one positions. For example, Deputy Prime Minister of Union of India cannot become Prime Minister in case of his sudden demise.