Normally, in undergraduate degree programs, depending on the respective program curriculum, a final year project is called "Final project dissertation". For postgraduate degrees (MSc/MA etc. and PhDs) the term Dissertation and Thesis are interchangeably used. For example it is called a Dissertation for MSc in......, or Doctoral Thesis/Dissertation. However, a research paper can not in any way be called a Dissertation nor a Thesis. You will probably call it "Final Research Paper". How was it called in your program curriculum?