There may be few differences in how the actual spells are cast today as compared to centuries ago, however there are many differences some spells have been up dated as time has marched on to fit the world that they would be cast in and expected to work. There is also the availability of some of the materials that could no longer be found and have been replaced with materials that can be found.
Throughout history back to ancient times there have been people that have been adept in casting spells and during that time these people would either be someone that everyone in the village would seek out for assistance in all types of life's problems and then there were the times in history when people who cast spells as well as those who were blamed for casting spells were sent to their death. However, during those times it was often the fate of these unfortunate people to be tortured to tell that they were casting spells and that it was devils work.
This of course is untrue and anyone that is involved in white magic and casts spells also follows their religion closely and has nothing what so ever to do with evil or the devil, all though these spell casters of the past could not have convinced their persecutors of this fact and many were put to death.
As early as 560 B.C. there was evidence to the people that the Bible condemned witches or those who possessed the power to cast spells and it was believed they should be stoned to death.
There is many other of these incidences such as the witch trails in Europe in the mid 1400's and again in the 1500's even to the point that in 1591 King James of Scotland authorized the torture of suspected witches.
Then of course in the United States there was the famed Salem Witch Trials where more citizens of the towns were convicted of casting spells and being witches than the citizens that were not. This saw person after person in the towns torture, put on trial and put to death, many of whom had never cast a spell in their lives. People that would not have the knowledge or power to cast a spell and all this was begun by children.
Today this has changed; there are places that readily sell the materials needed to cast spells, spell books and other supplies. There are advertisements in newspapers and telephone books as well as the Internet where those who have the knowledge to cast spells will do this for others.
There are even movies and books where spell casting is the main characters specialty and there is little thought about it with the exception of those whose religion is so strict that spell casting is still though evil.