DELF and DALF: the certificates that last
DELF and DALF are issued by the French Ministry of Education and, unlike the tests used for immigration, they never expire. Between them they cover the whole CEFR scale, and you sit the one level you want rather than a test that places you.
One exam per level
DELF covers A1 to B2 and DALF covers C1 and C2. There is a separate exam for each, you choose which to enter, and below the pass mark you get nothing - no lower certificate as a consolation. Entering a level above your real one simply loses the fee.
Four papers, and the minimum in each
Each exam has the same four papers - listening, reading, writing and speaking - each marked out of twenty-five. You need fifty out of a hundred overall and at least five out of twenty-five in every paper, so one abandoned section fails the whole thing however well the rest went.
TCF and TEF work the other way
TCF and TEF are the other two you will see, and they work the opposite way: no pass or fail, just a score placing you on the CEFR, valid for two years. That makes them the ones used for immigration and for Canadian applications, where a current score is what is wanted.
Which one to sit
So the rule of thumb is simple. If the certificate is for study or for your own record, sit DELF or DALF and keep it for life. If it is for a visa or a points-based application, sit TCF or TEF, and sit it close to when you need it rather than years ahead.