Lieutenant is generally used in the military. Deputy is generally Law Enforcement (Police etc). Outside of that, there is no standard, it's just titles.
vice- is used for something that can take the place of something. So the vice-president will take the place of the president in an emergency if the president dies.
Deputy is like the number 2. The second person in charge.
Lieutenant is the really difficult one, Lieu means in place of, so it is often the person second in command. But it depends on where it's being used. A lieutenant in a police force is a high rank, a lot higher than a lieutenant in the army...
A little off, but I've been wondering what the standard pronunciation for "lieutenant" is. I was taught to say "leftenant" but everyone here (in the U.S.) says "lieu-tenant" (as it's spelt).
In Commonwealth countries (UK, Australia, New Zealand...maybe Canada)
you say "lef-tenant". In the U.S. it's "loo-tenat". It derives from a French
word and I wouldn't have a clue how they pronounce it.
My potted history according to Hornblower is that Lieutenant were a rank
beneath the Captain of the ship. If a ship were surrendered by the enemy
or taken as war bounty a lieutenant with a group of marines would take
command of the ship and return it to England or a nearby friendly port
where the prisoners could be handed over.
~ Ian, in Canada they will say lef-tenant on the news, or in conversation if you are talking about the government title, and if you are in the military I think you say lef-tenant too, but we are so american now that I say loo-tenant without thinking about it. :.-(
ahah, for all the ESL people reading this (native speakers: wait!), a bonus question: