Bitcoin Forum

Here is a dumb question :
when I look up my public address on Ian Colemans key compression site , the resulting addresses ( compressed and uncompressed ) yield different balances ,
where the uncompressed address has funds , and the compressed shows 0 balance
is this normal ?

That's certainly normal (since it's IanColeman's compression tool, it must be P2PKH).
Although both correspond to the same Private Key, Bitcoins aren't stored using the private key but through a "locking script" which is represented to you by an address.
So simply by knowing that the compressed and uncompressed addresses are different than each other explains why each has different balances because the bitcoins are locked using different scripts.

The HASH160 which is part of the locking script is derived from the public key.
Compressed and uncompressed public keys are different from each other (as you can seed in the tool) so both wont produce the same HASH160 result,
thus, different locking scripts for the compressed and uncompressed.

In simplest terms, a public key can have two forms: compressed and uncompressed. An address is a hash of a public key, so you can have two different addresses from the same private key, one is a hash of the compressed public key and the other is a hash of the uncompressed private key. They are distinct addresses and are not interchangeable.