The Middle Paleolithic period is a cultural period ranging from 300,000 to 45,000 years ago. Neanderthals were already around since about 600,000 years ago, but it is in the Middle Paleolithic period that the first appearance of Neanderthals in Europe occurred. Besides the emergence of Neanderthals, the emergence of anatomically modern humans occurred during this period as well, around 195,000 years ago. Anatomically modern humans are defined as individuals with an appearance consistent with the range of phenotypes in modern humans.
The Upper Paleolithic period ranged from 50,000 to 10,000 years ago and coincides with some thing called the Last Glacial Maximum which is the coldest phase of the last glacial period (24,500 to 17,000 BC), before a relatively rapid period of warming. Although the Upper Paleolithic was during this glacial period, there were still parts of the world that were not covered in ice called the Last Glacial Maximum Refugia. Research has shown that there was a lot of human activity in these areas because they could still be inhabited.
Besides being a lot warmer than the Upper Paleolithic, there are many differences between these two periods and their different types of technology. One example is their sustinence in each period. Although both periods (the entire Paleolithic period actually) had hunter-gatherer sustinence economies, the Middle Paleolithic supplemented their diet with fish and shellfish. There was also evidence of people drying and smoking their food for preservation and storage during this time. During the Upper Paleolithic, their tool technologies advances and allowed them to hunt larger animals such as mammoths, cave bears, and wooly rinoserouses.
During the Middle Paleolithic, their technology was primarily stone tool based. They had two stone tool tradition periods, the Mousterian and the Aterian. The Mousterian period, which was primarily associated with Neanderthals in Europe, North Africa, and the Near East between 300,000 and 30,000 years ago. Their stone tools were much more sophisticated than the tools of the Lower Paleolithic, with bifacial point designs as their main form of tool. The Aterian period, which was associated with anatomically modern humans between 80,000 and 40,000 years ago. This period was well known for its tangled projectile points which had a little bit at the bottom that could be mounted on a spear shaft. This tool type is much more advanced than the rocks with a sharp edge of the Lower Paleolithic.
Even more advanced still were the tools of the Upper Paleolithic period. The Aurignacian stone tool tradition period, between 45,000 and 35,000 years ago, featured blade-based stone tools. The Solutrean stone tool tradition period, between 22,000 and 17,000 years ago also featured blade-based stone tools but they also featured a double ended scraper, so the blade-based tool of the Aurignacian period has clearly evolved. This makes sense because as the tools evolved from the Middle to the Upper Paleolithic periods, people became capable of hunting bigger animals.