@Proxima The two functions (Amplitude Envelope Correlation and Envelope Correlation 2020) use the same article as the reference to compute the amplitude envelope correlation.
https://www.nature.com/articles/nn.3101
However, the 2020 function has more features including the ability to compute the frequency domain by Morlet wavelet, splitting the large data into smaller pieces, using the Parallel Processing Toolbox, calculating other connectivity measures, and employing moving average window for dynamic connectivity. We are working to prepare the A x B case for the 2020 function.
In case you use Hilbert transform, window length equals signal length, and the static case for the 2020 function, you should get identical results with the older AEC function.