# Isn't Gardner's algorithm and Early-Late gate the same thing?

I'm reading about some symbol synchronization methods and I find these two (ELG and Gardner) very similar.

Early-Late gate takes 2 samples, one at $$t=T-\delta$$ and the other at $$t=T+\delta$$, then from that you get the timing error; Gardner takes also 2 samples for $$\delta=T/2$$, one at $$t=T-T/2$$ and the other at $$t=T+T/2$$.

I can't really see the difference between these two, although there must surely be a few. Could someone explain that to me?

Thanks.

Note that the Gardner Timing Error Detector forms a Timing Error Discriminator by approximating the derivative of the waveform at the assumed zero crossing and weighing that by the actual sample value at the crossing location. (The difference equation $$y[2n+1]-y[2n-1]$$ is an approximation of the derivative).