huge difference! for me, jelly is horrid, it offgasses its nasty chemicals and burns my vagina in a way that won't go away. as the toy degrades over time, it breaks down, and those chemicals go straight into sensitive orifices. my first jelly toy i used WAY longer than i should have, and often without a condom. it eventually got so bad i couldnt even use it WITH a condom without its burning properties seeping through it and hurt me.
also, jelly attracts lint and dust, won't last long because it degrades over time, and picking lint out of it causes divets in the material. also you can't sterilize it because it's not boilable and it is porous.
glass is very hard, so needs to be used with care if doing DP or if using a toy with texture. check out some of my reviews i'll link below on glass toys to see what you might like.
glass lasts FOREVER, is very hard to break, is so easy to clean and sterilize, and will never burn you. it's just not as flimsy and doesnt have 'give' like jelly. if you want a toy with give, to be softer on your insides, or for use during DP or with texture, get silicone. it's your safest bet, and it will last you a lifetime. silicone is sterilizable and all the lovely things that glass is, too.
doc johnsons reflections, cool
p.s. the 'jellyfish' is made from silicone!