It depends on what you want to take the exam for.
The DELF/DALF are diplomas that validate the language skills of a French as a foreign language individual and are valid for life. It is needed for those who wish to get a job in a French speaking country, enroll in a French university, and it can also be used to justify your language level when applying for French nationality.
The TCF and TEF is a certificate that verifies the language skills of a French as a foreign language individual and is valid for 2 years. It is needed for a request for French nationality, a request for a long-term resident card and a validation of level A1 as part of the Ofii citizen course. The main difference between the TCf and TEF is the actual exam.
For more information refer to our exam pages, and do not hesitate to contact us.