The PS2 was getting games years after the PS3 was released.
As far as games being "the same with better graphics," no. Look up what RAM means and you'll see the difference.
Here, I'll help you out:
When Sony stepped out in New York with the surprise revelation that PlayStation 4 had a whopping 8GB of very fast GDDR5, there were few people more pleased than Dishonored's lead level designer Christophe Carrier.
"We need memory, you know?" he shrugged, smiling knowingly at colleague Dinga Bakaba after winning Best Game at the BAFTA Game Awards on Tuesday night.
"As a level designer we are struggling against memory every day. We cut things, we remove things, we strip things, we split the levels, we remove NPCs from levels because there's not enough memory.
"So knowing that memory is something that is going to be improved in the next generation of consoles: to us, it's a joy. It's something that we were waiting for.
"We were PC gamers at the beginning. We love PC games, and we had to make games on consoles. But the main problem was memory. The processors are good, but the memory, for our games, is the most important. So it's great." -- http://www.eurogamer.net/articles/2013-03-08-dishonoreds-lead-level-designer-labels-ps4s-8gb-ram-a-joy
