You are not asking an ignorant question by no means.
It is possibly the one of the most important questions that we are facing since Vatican 2, and is often so confusing that it takes a theologian to figure out the details. Behind the theologian will be a canon lawyer to determine what is valid and what is not, when certain practices at Mass become questionable. It is a question that often presents more opinion than fact and I caution you to be very inquisitive as to the sources that you get information from. Be certain they are in communion with Rome herself and in full approval of the Magisterium of the Roman Catholic Church.
The varied opinions that will undoubtedly be generated by such a question should be first taken into consideration. The Pope has informed us that the two rites are the same. Some individuals will beg to differ, and this is where a great deal of confusion is generated. One can spend a great deal of time and energy attempting to prove one is not as valid as the other. Sadly, this is a waste of precious time in which we could have used for more useful and holy exercises.
Understand the meaning of the Sacrifice of the Mass, do some historical research, study Church documents of pre and post Vatican 2, and you will get a clear picture of why the two forms are different. Much of it has to do with a great deal of modern thought and its supposed necessity in keeping the faithful increasing in faith, and attracting other souls to the Church through the use of familiar ground and worship actions and atmosphere.
The idea of what Mass is should first be established and clear to your understanding, and then you may form an opinion based on a great deal of research into the evolution of the Mass, and of the various councils that the changes were instituted thereby.
There is a great deal of information available on your question if you are willing to do a little detailed research. It may be the greatest research that you can do.
