For most amino acids, the L form corresponds to an S absolute stereochemistry, but is R instead for certain side-chains.

Is S and L configuration the same?

The main difference between L, D configuration and S, R configuration is that the first one is relative configuration while the second one is absolute configuration.

Are all L amino acids s?

All of the naturally occuring amino acids are called L because they have a stereochemistry that was historically correlated with one stereoisomer of glyceraldehyde, shown below. L-Glyceraldehyde and the natural amino acids all have the S absolute configuration. The two exceptions are glycine and cysteine.