Use a juicer if you have trouble digesting fiber. Blending a smoothie uses every part of the fruit you put into it, including the fiber, which makes it a healthier option for most people. Avoid juicers for avocado, bananas, pineapple, yogurt and protein powder. Either add these ingredients to your juice or reach for your blender. Since these ingredients do not have a high volume of water content compared to their pulp, they may not be able to break your juicer, but most of the fruit will be thrown away with the rest of the pulp.