If you're comparing the two side by side close up the difference is obvious, but I guess that's not much help to you!! If you're running sintered glass you'll need good mechanical filtration or the fine pores will eventually become clogged and you'll lose a lot of the benefit from the expensive media. They also break down over time, I have some Siporax that is ~12 years old and is so thin and fragile I can crush it between my fingers with little effort. It's actually a real PITA as I have to pick it out of my ceramic noodles as I don't want it breaking down any more in my filter...