Both are similar, look at the details such as slam latches vs. turn latches on the outside compartment doors. The quality of the cabinet hinges, fit and finish of the details like faucets, trim, etc.
the Sierra also offers some different standard packages, depending on your needs and wants, insulation, etc.
Take the time to look it over, check actual models if you can and walk through them.
Mark, Vicki, & Scout THE dog
2015 Hemisphere 282RK
2010 F250 Super Duty
1992 Goldwing Aspencade