Dear LizInCali,
Thanks for your post!
The rumors you've heard are generally true: the top full-time programs are typically harder to get into than their part-time counterparts. This is evidenced by the higher average GPAs and GMAT scores and lower acceptance rates across the board at top full-time vs. top part-time offerings.
One factor at play here is that the full-time offerings are typically less 'regional' than their part-time counterparts, broadening the applicant pool to the entire globe vs. a more localized market. Of course, this does not mean that the part-time programs aren't worth looking into, nor that they are 'easy' from an admissions standpoint.
In a nutshell, the part-time experience is generally more tailored to someone who is remaining in their current field and looking to accelerate their career. In fact, many part-time MBA students are reimbursed by their employer for some or all of the tuition fees. Full-time programs offer more of an immersion experience, enabling students to make a clean break from their prior experiences and enact a career change if they so desire (many use the programs to accelerate their existing careers as well).
Best of luck,
Graham