I use these in different ways to get the best advantage from them;
Bubble wrap I use as a lining to the greenhouse only, and as someone said it has a tendency to create condensation this is not good for plants.
Fleece is not much good as a lining at least for temperature control but is quite good for shading.
Fleece is best used on top of the plants as this gives minimum air space between the general area of the greenhouse and the plants.
As it is light enough it does not do much damage when lying on the plants although some wire hoops to form a cloche is even better.
Note: the same applies when you are using it out doors keep it off the soil otherwise it acts like a wet Tee shirt and does very little good at all.
Another thing in favour of fleece is its cheaper.
This might be true but there are basically two types of fleece 'spun & woven'
Spun is much cheaper but does not last very long (possibly one season) woven is stronger and a bit more expensive but it will last for a few years given care.
Just thought I would mention this!