Blending vs juicing (very simple talk)
Blending
The nice thing about blending is that you can blend low water content foods that you would never be able to juice. Blending is also considerably quicker and can be much easier to clean up afterwards than some juicers. The drawbacks are that blending oxidizes food alot more and seems to interfere with the energetic quality of the food. But if you don't have the time to sit down and chew your food very thoroughly, you should blend it. Just make sure to still chew and swish the blended food around in your mouth for optimum digestion.
Juicing
Juicers only work with foods with a high water content, aka fruits and vegetables. The juice they create has no fiber, which has both advantages and disadvantages. The nutrients are absorbed many times better without the fiber, but if you are juicing a lot of fruit than the lack of fiber becomes a detriment and it is like drinking sugar water. The main advantage of juicing is that is saves your body huge amounts of energy that would otherwise have to be spent on digesting all of the fiber in the food, which is why juicing is ideal for cleansing and fasting.
I mentioned that blending oxidizes the food a lot more than juicing, but juice also oxidizes much faster than blended food. Sound confusing? It works like this: when you blend a food, the act of blending itself will significantly oxidize the food, and after that the blended food will continue to oxidize at a moderate rate as time goes on. When you juice a food with a good masticating juicer, the act of juicing will hardly oxidize the food at all. However, since the juice has no fiber, the juice will oxidize very very rapidly after it has been made. The moral of the story is that juice should be drank immediately after being made, and although it's still best to drink blended food immediately, you have a little more leeway than with juiced food.
You get far more benefits out of vegetables if they are juiced than blended, but it is better to blend fruits than juice large amounts of them.