Will was curious about all things to be baby proofed by 7 or 8 months. He would crawl towards cords, open cabinets and climb the stairs. We had to baby proof everything we could. We even tethered furniture to the walls due to his love of climbing.
Katie is just content. She can sit and play with a toy for quite a while. If you redirect her, she is fine with doing something new. It is amazing how these two can be so different!