Why are different private and public key generated in online brainwallets? Why is that different wallet generating sites give different public and private keys when you enter the same passphrase even though they both use the same Algorithm (Sha 256)?
Thank you
P.S.
Ok...one site is bitaddress.org and the other site is walletgenerator.net. i tried getting a brainwallet and used the exact passphrase but got different keys. The passphrase was: robertarmenkery.
Obliged
They are the same, bitaddress.org uses an option that you missed; compressed and uncompressed addresses. Turn the compressed address on, then you will get the same values.
They both use base58 while displaying the content when converted to hex
uncompressed
pub  00515da4ade2ea43379043341d158ba1637e695c7b9d942422
priv 8012e29482949d92ef7c159f27065ef7bda744cc0dde8551cc324b312ce6736e24 7af43428

and compressed
pub  00b3f704fd7f30d5868f0e070b7adf75703313775717588aa4
priv 8012e29482949d92ef7c159f27065ef7bda744cc0dde8551cc324b312ce6736e24 01 3445217c

0x08 is always prepended, 0x01 is the indicator for the compression, and the last 4 bytes are trimmed double SHA256 checksum.

Note that generating your private key online is really really a bad idea.