I honestly have no idea what is so difficult about this. Does a laptop with a 256 GB SSD and 8 GB of RAM uses both completely interchangeably?
Manufacturers are not obliged to divulge all technical specifications. And for smartphones, RAM (and processor speed) are sometimes not made public but once you have rooted a device, it is easy to install software that can extract these parameters.
Here are the tech specs for all iPhones:
http://en.wikipedia.org/wiki/Iphone#Model_comparison
RAM (also called memory): 512 MB
Flash storage (also called storage): 16/32/64 GB
Here for the Samsung Galaxy S III (start with the sidebar on the right):
http://en.wikipedia.org/wiki/Samsung_Galaxy_S_III
RAM (also called memory): 1 or 2 GB depending on the version
Flash storage (also called storage): 16 or 32 GB