Casino chips come in a variety of styles. Every casino
has its own design - and often multiple different designs - to differentiate them from each other. They are made from a variety of different materials - from pure clay chips (Rare these days) to clay-plastic composites, to pure plastic, to plastic-wrapped metal, to metal alloys.
Yet, for all their differences, all casino chips have some things in common. All chips are approximately the same size. $1 chips are usually metal, and slightly smaller than other denominations. They all weigh almost exactly the same, so that you can put $1 chips from one casino into a dollar Slot Machine at another. $5 chips are red. $25 chips are green. $100 chips are black. $500 chips are usually purple, but many casinos don't even have them, so there is no real consensus on what color they should be. Larger denominations do exist, but I've never seen or dealt with them. Some casinos have $5 chips for slot machines. These are metal (often bronze or gold electroplated), and noticably larger than other chips.
It is against Nevada law to use casino chips for any purpose other than gambling. Some casinos have written policies that say that they don't accept chips from other casinos, but in all cases, the unwritten policy is that they'd rather take the chips than have you leave the casino.