Problems faced with the conversion from IPV4 to IPV6 addres by two techniques I.E 6to4, it uses a one IPV6 address prefix, and 6rd,unlike 6rd by IPV6?

A 6rd domain consists of 6rd Customer Edge (CE) routers and one or more 6rd Border Relays (BRs). IPv6 packets encapsulated by 6rd follow the IPv4 routing topology within the SP network among CEs and BRs. 6rd BRs are traversed only for IPv6 packets that are destined to or are arriving from outside the SP's 6rd domain. As 6rd is stateless, BRs may be reached using anycast for failover and resiliency