Thank you D for your reply.  So if we go with the DC, what do I need to have electric crossing guards.  My son really wants crossing guards that lift on their own as a train approaches. 
I think I understand the difference now between DC and DCC.  At this point he is going to only have one train track with one train so maybe I can go with the DC train set.  I really need to now how to make these crossing gates lift on their own.

Thanks
New to Trains

My son is wanting a HO trainset for Christmas.  He is looking at the McKinley Explorer or a Digatally Command one.  My question is, which train set will allow him to add crossing guards that are activated by the train and eventually add other sounds and lights. We don't understand the difference between the basic speed control and the digital stuff.  Do we need the digat control train set or would the regular work out fine.  Help...