No, I don't. I just wonder whether they're full synonyms or have some differences. If you insist, we could consider some sentence. Like this, 'In most cases, the walls and floor of your pool feel slimy and slippery due to a lack of pool maintenance.'.
Pool walls can become slimy if mold is growing on them. They can also be considered slippery, but I would only use it for surfaces I was walking on -- rocks in a stream or floors or other flat surfaces, for examples, but not walls. Even though slimy walls would be slippery to the right creature (Spiderman?), we tend to look at things from our own perspective and most of us don't walk on walls yet.
I can also see something called slippy as a change from slippery -- especially if it were a children's story: They waded across the stream on small flat rocks that were slimy and slippy. (Slippy because you slip on them.)