Hi PaulineD
What a good question - let me shed some light on the answer.
America's National Parks and Canyons is a 10-day tour and visits 3 national parks, 2 canyons and other places of interest which aren't technically a national park or canyon.
National Parks, Mount Rushmore & Little Big Horn is a 17 day tour and visits 6 national parks, 2 canyons and even more places of interest.
We have run both tours (or variants of these tours) alongside each other for a number of years as they both offer travellers the opportunity to see some amazing landscapes, however we have recently found that the longer tour has become much more popular and a decision has been made to rest the shorter tour for now.
Hope that helps explain things a little bit.
Kindest regards,
Julia