interface vs ip

["P theodorou" <props666999@xxxxxxxxxxx>]

Im new to this therefore i need to clarify the followings

1)can i send or recieve packets from interface to ip and vise versa

or  only to interfaces and only to ips

2)

I want to let icmp packets from 192.168.0.1(eth1) to 192.168.1.1(eth2)

is it safer to declare

iptables -A INPUT  -i eth1   -o eth2 -J ACCEPT

or
iptables -A INPUT -s 192.168.0.1 -d 192.168.1.1

Thank You