Tempo runs (sometimes called threshold runs) are runs where after a 10-15 minute warm up you run at a sustained pace for anything from 20 min up to an hour with a 10-15 min slower jog at the end. You are running hard, possibly just below your normal 10k pace, but not flat out. And the distance and effort should be such that you do not finish feeling exhausted. As with interval runs, it is such an individual area, to recommend individually.
Pace runs are training runs, run at approximately your estimated race pace. That is if you are aiming for a 3 hour 30 marathon averaging approx 8 min miles.(5 min km) then your pace runs are run at 8 min miles. They help build pace judgement and even paced running. The long training run is there to build endurance, not speed, and running your long run at a faster pace than you are ready for could lead to you taking longer to recover each week and upset the steady gradual improvement all schedules are designed to bring.
Repetition/Interval training (8×800)
Repetition or interval training are a feature of schedules where you are really committed to improving and bringing the best out of yourself whatever your standard. You do not have to be an elite or even good club standard runner to run the advanced schedules. Rather you have probably a background of a few years of training fairly hard at any distance from 10k up to marathon and understand how faster paced running or running “out of your comfort zone” once a week has helped you improve.
Interval or repetition running, are efforts run at faster than your planned marathon race pace. Impossible to give more than general guidance as it is such an individual area and depends a lot on where you are starting from and what your goal is and is usually best done under guidance from a group environment or a coach or experienced personal trainer. 4x 800 is one example which can build to 8x 800 as the schedule progresses. You run the 800 metres or whatever the chosen distance is at the faster pace. Then walk or jog 400metres very easily before repeating the faster distance again etc. For marathon training long intervals of at least 800m or longer (1000m or even a mile) are acknowledged to be most beneficial.
These are a variation on repetitions on the flat. They are a great variation with a similar benefit of building leg strength. Find an incline of approx 4-600 metres or one that will take about 2 minutes. Run hard up the hill and slightly over the crest, turn around and jog slowly down the hill before repeating the run up again etc