There is a difference between a walkout basement and an exterior access.
With a walkout basement you are walking out to grade level (i.e. no stairs); with an exterior access there will be stairs to walk up to grade level. Now you know!
Hot Tip #3
We can't answer legal questions for you, but we have a place to send you.
The Illinois Association of Realtors® (IAR) has a free legal hotline. However, you must either be the IAR Designated Realtor (called the DR, i.e. owner or manager) or have been designated by the DR of your office to be the legal hotline contact. Click HERE for the details.