It's quite easy to find these using Google, but I've found these Cisco docwiki references helpful:
Basic IPv4 BGP comparison
As a taster, here is part of our BGP configuration for a distribution router in IOS:
router bgp 64602
bgp router-id 192.84.5.248
no bgp default ipv4-unicast
bgp log-neighbor-changes
!
neighbor core_peers peer-group
neighbor core_peers remote-as 64602
neighbor core_peers update-source Loopback0
neighbor core_peers timers 10 35
!
neighbor 192.84.5.240 peer-group core_peers
neighbor 192.84.5.250 peer-group core_peers
!
address-family ipv4
neighbor core_peers send-community
neighbor core_peers soft-reconfiguration inbound
neighbor 192.84.5.240 activate
neighbor 192.84.5.250 activate
maximum-paths 2
maximum-paths ibgp 2
no auto-summary
no synchronization
exit-address-family
!
address-family ipv4 multicast
neighbor core_peers send-community
neighbor core_peers soft-reconfiguration inbound
neighbor 192.84.5.240 activate
neighbor 192.84.5.250 activate
exit-address-family
... and here's the equivalent in NX-OS:
router bgp 64602
router-id 192.84.5.248
log-neighbor-changes
!
address-family ipv4 unicast
maximum-paths 2
maximum-paths ibgp 2
!
address-family ipv4 multicast
maximum-paths 2
maximum-paths ibgp 2
!
template peer core_peers
remote-as 64602
update-source loopback0
timers 10 35
address-family ipv4 multicast
send-community
soft-reconfiguration inbound
address-family ipv4 unicast
send-community
soft-reconfiguration inbound
!
neighbor 192.84.5.240
inherit peer core_peers
neighbor 192.84.5.250
inherit peer core_peers
You can see that peer groups become templates and the parameters for each address family with a peer are configured under the peer (as part of the template) rather than the address family block directly under the BGP process.
