When you try to find the difference in words that seem similar - check an English/English Learner's Dictionary. They are better than a thesaurus in explaining the differences in words, because they are written especially for foreigners who need a guide to nuances in the language a native does not need. 'believe' - means 'to be quite sure or certain of something without having an actual proof of it. In detail here are all possible angles to look at 'believe': 1 [transitive] - to feel certain to feel certain that something is true or that somebody is telling you the truth 2 [intransitive, transitive] - think possible to think that something is true or possible, although you are not completely certain 3 [transitive] believe (that)… - have opinion to have the opinion that something is right or true 4 [transitive] - be surprised/annoyed don't/can't ~ used to say that you are surprised or annoyed at something 5 [intransitive] - religion to have a religious faith 'trust' - has a few meanings, the first given here compares most to 'believe' The difference is that to trust someone you must have the 'belief' that this person will not harm you. 1 [uncountable] trust (in somebody/something) the belief that somebody/something is good, sincere, honest, etc. and will not try to harm or trick you 2 [countable, uncountable] (law) an arrangement by which an organization or a group of people has legal control of money or property that has been given to somebody, usually until that person reaches a particular age; an amount of money or property that is controlled in this way 3 [countable] (law) an organization or a group of people that invests money that is given or lent to it and uses the profits to help a charity 4 [countable] (business) (American English) a group of companies that work together illegally to reduce competition, control prices, etc "believe in someone/something" can in its meaning be quite similar to 'trust'. It is a phrasal verb, meaning you can 'trust' someone to do the right thing and to be successful in what they do. A second maning is incorporated here: to think that something is good, right or acceptable The descriptions are a short form of the oup advanced learner's dictionary: http://oald8.oxfordlearnersdictionaries.com/dictionary

Believe in someone means you accept what they say and do but trust in means that you can accept what they say and do and so you have confidence in them and follow what they suggest. As for believe, it's similar to believe in in my opinion.