Comparing two Accelerometer signals in time domain
I suggest using a correlation metric as a comparison. Remove any mean in the signals and after subtracting the mean, compare the signals using the Pearson Correlation Coefficient to have a single data point that scales between +1 and -1 with regards to their direct correlation assuming any time offset factors have been removed, and even better as a first evaluation use the cross-correlation function which would provide the above (without normalization) for every offset in time, in case their are delays between the results.