what is the difference between cellulose and fiber?

cellulose is the material that composes cell walls. to that end all of the cells listed will show some red to varying degrees depending on the thickness of the cell walls.
parenchyma cells which are still living have very thin cell walls and the cell contents are still present meaning that you probably wont notice any red in these cells depending on what other dyes are added as well.
tracheids are dead xylem cells with moderate thickening of the primary and secondary cell walls. these will stain red
vessel elements are larger (diameter) than the tracheids but perform similar functions and the cell walls will look the same in a cross section cut. stain red.
fibers are also going to stain red and these will actually probably appear the darkest because the secondary cell walls are so thick they actually close up the cell so they will appear totally dark red.