Dear Blondie:
I see that no one has had a chance to answer your questions yet so I will give it a stab. Bear in mind that I am far from an expert and if anyone subsequently reading this feels I need correction, I urge them to do so.
Muscle strength is defined as the ability to lift a really heavy weight for a limited amount of repetitions. An extreme example are those huge guys that hoist an enormous barbell over their head, hold it for a second and then drop them towards the ground. I don't know what this is called but I am sure you have seen it on television sometime.
Muscle endurance is defined as the ability to lift lighter weights for much more repetitions or any activities that require prolonged use of a muscle group, such as running or step benching.
Exercise tapes involving barbells and dumbbells all promote strength gains and endurance gains. However, one type of gain is usually predominant. A clue to tell which is which is to look at the amount of reps in each set. For instance, in Pure Strength, most sets are two or three consisting of 10 reps. That would favor muscle strength. In Slow and Heavy, you use your heaviest weight possible and do 8 reps. That also is muscle strength. You will gain endurance too but the focus of these videos is to gain strength.
Maximum Intensity Strength is a little bit of both. Some of the exercises have more reps than Pure Strength but still use rather heavy weights.
Power Hour is mostly endurance, although it too will give you strength gains. Lots of reps here, lighter weights.
So, what's the difference in how it affects your body?
Everyone is different and we all react uniquely but in general, muscle strength creates larger muscles. Endurance usually creates a toned look. Some also say it helps to get cuts, or definition too, once you have acquired your muscles through strength training.
I think Jillybean was correct in advising you to use Power Hour twice and MIS once each week. That rotation will give you an opportunity to get three full body training days with a combination of endurance and strength.
If your goals are to lean out, then I suggest cardio at least four times a week in addition to weight training. If you want a toned, sleeker look, Power Hour is a good choice. Once you have achieved that and then desire a more muscular appearance, switch to Pure Strength and Slow and Heavy.
I started out just wanting to lose some weight and tone up. When I began to see some real muscle development here and there, I got inspired to get more. Don't be afraid of training with heavier weights. Most women cannot develop really bulky muscles.
I hope I have adequately answered your questions about strength vs. endurance.
Marlene
Wendy