The result certificate is a local document, generated by the school. Often contains the marks if applicable. It is a kind of "temporary" document. The diploma is the corresponding national document, generated and signed by a central authority. No marks are mentioned usually. It is a kind of "final document". There is also sometimes a phone number behind it anyone can call to check whether it is true or fake. However, I personally have several 20 years-old result certificates from the university, and never went to collect the diploma. It never was a problem for finding a job or even for studying in other universities.