What is difference between Wild Card mask and Subnet mask?

As of use both wildcard mask and subnet masks are same but

- when we are calculating subnet mask  we make network bits = 1 and host bits =0  . ex. ip = 11.11.11.11 subnet mask = 255.255.255.240 here numbers of 1's = 28 so we can say number of network bits in ip address are 28 and rest 4 bits are hosts bit.

- Wildcard Mask can be calculated as network bits = 0 and host bits = 1 so we can say that  wildcard mask is just oppsite to subnet mask.

while some protocols like eigrp , ospf ,bgp use wildcard mask in their network command to enable these protocols on specific interfaces instead on complete router .

ex. ip = 11.11.11.11   its subnet mask = 255.255.255.240 so its wildcard mask will be = 0.0.0.15

how to calculate wildcard mask from subnet  mask in above example =  first ocet( 255-255 ) . second octet ( 255-255 ) . third octet ( 255-255 ) . fourth octet ( 255- 240 ).

now Routing Protocol uses wildcard mask :

example in eigrp : 

network 192.168.1.0 0.0.0.3    will enable eigrp on interfaces having ip addr 192.168.1.1 and 192.168.1.2

But initially ACL's were invented and they use wild card mask and then subnetting came into market with subnet mask that's why we use both.