Postman was an easy-going box. It required careful enumeration and beyond that did not have too much resistance in privilege escalation. This makes it a prime example for real-world M&M security where the initial foothold is hard, but there is few resistance on the inside.
Wall was as much a fun and educational box as it was frustrating and stretching my patience. It felt like the system was updated by the creator to have some features in place meant to annoy people trying to break in. Nevertheless, there are some nice WAF evasion techniques to consider here, as well as the lesson to never give up on enumeration.