Explanation/Reference:
B: You configure Layer 2 VPNs in a routing instance. As a result, Layer 2 VPNs have unique site and VPN identifiers. However, Layer 2 circuits do not require a routing instance configuration and instead use an alternate method of identifying circuits.
D: Layer 2 VPNs, like Layer 3 VPNs, require Border Gateway Protocol (BGP) for transport of traffic between PE routers. In contrast, Layer 2 circuits do not require BGP. Instead, Layer 2 circuits rely on LDP and MPLS for their operation.
References: http://www.juniper.net/techpubs/en_US/junos12.3/topics/concept/layer-two-circuits-overview- solutions.html