Is the silicone used in anal toys different than the one used for vaginal toys?

I can answer this question specifically, no idea about egg vibrators in general. If it is actual silicone (and be careful, a lot of cheap Amazon sex toys are not actual silicone), then it's non-porous and body-safe. In terms of pathogenic safety, any silicone toy can be used both vaginally and anally, and shouldn't grow bacteria/mould/etc inside it. Toys made specifically for anal will be made of harder silicone to make sure it can penetrate, and you probably know this but should have a flared base for anal. But some toys designed for vaginas also satisfy those qualities.

Actual silicone can be safely boiled. I boil my dildos to disinfect them (after washing with soap and water first). I use gentle pH-neutral soap so as to not damage the toys.