Let me try explaining some of the Key differences:
1. Slot Capacity: 4510R is a 10 Slot chassis while 6506 is a 6 slot chassis.
2. Power Supply: 4510R and 6506 both supports power supply redundancy while 6500 has a wide variety of PS like 4000W,6000W,9000W.4510R has max4200W PS.
3. Backplane:4510R supports at max 136 GBPS backplane capacity with Sup-5-10GE while 6507 supports 720Gbps switch fabric.
4. 10GE Scalability: 4510 has limited 10GE only 4 ports at MAX with only 2 active at one time. 6506 offers a wide 10GE ethernet scalability.
5. Service Module: 4510 doesnot support services module while 6506 supports a wide variety for service modules like Firewall, IDS/IPS, ACE,CSM, WAN module etc...
6.Architecture: 4510 supports centralized architecture while 6506 supports distributed architecture.
There are a lots of more differnces. Please find the datasheets below for more undersatnding.
HTH,Please rate if it does.