For example 'ändern' and 'verändern': <Ändern> suggests a change in a general way, without any indication of its degree or extent: <Ich habe meine Meinung geändert>. A partial, usually slight change, a modification, is implied in <abändern>, the change being properly effected by taking off or away what is imperfect. A more thorough, but not necessarily radical change is suggested by <verändern>, especially common as a reflexive with intransitive force: <Seit dem Krieg hat sich die Stadt sehr verändert>. And much the same is conveyed by <umändern>, pointing especially to the resultant state: <die Küche in ein Schlafzimmer umändern>.

Sometimes there's a difference, sometimes there isn't. After learning a large number of them the meaning of "ver" becomes clear. There is really no need to jump the gun here. Just be patient and learn them one by one. One of the meaning s of "ver" is: "~ate". It is used, as in English, to turn a noun into a verb. But that is just one of them. That should get you started.