The content, such as cards or special drops, of a crate is decided by a special formula when the crate is opened. The formulas will be publicly viewable on the blockchain allowing for full transparency and guarantee of scarcity.
Until each crate is opened the crates are all the same. They are fungible tokens (FTs) meaning they are identical and interchangeable.
Specific cards are not limited to a pre-defined count, this means that every crate, from the first to the last, has an equal chance of drawing every card. The special drops work slightly differently, see The special drops.