They can be used interchangeably as every "network" is a subnet of 0.0.0.0/0 and every subnet is itself a network. And this the exact thing I want to point out, I read this doc and understood that the answer by Bikram sir is right. But the thing that I want to emphasize is on is, will GATE ask questions on classful addressing as it is obsolete and questions like these are getting more confusing as we have answers which says doesn't subtract 2 from number of subnets and hosts which is "obsolete" according to above doc. "Read the last two line above references"
*Subnet all zeroes and all ones excluded. (Obsolete)
*Host all zeroes and all ones excluded. (Obsolete)
So, now does it mean that no. of usable hosts equal to 2^host-bits (without subtracting 2 from it)