I think that in the back of the owners manual it explaines it. My Kids Sporty has the Proximity & He loves it  he never has to remember to set it. Not that's a bad thing. ya know buy 'um books, send 'um to school & they're still dumber than a fence post.

My Road King has the push button but ya damn near gotta be next to it to get it to work. 

If all else fails chek W/ your dealer.

John