The fact that the topic always arouses (aroused) controversy, however, the answer is as short and as simple as the construction of a hammer
and does not require a paper, although I have translated and drawn charts more than once to explain and visualize this small nuance ... But to the point:
The alternating current changes amplitude (whether periodically or quite randomly) with respect to time, but it does not change direction (the direction of flow is constant) - it does not pass through the time axis through zero - although of course it can be zero.
The alternating current changes with time and in amplitude and direction. A certain case of alternating current is the power grid - but here we are dealing with periodic alternating current (sinusoidal in nature - one half of the sine wave is positive and the other half is negative), but there can also be rectangular, triangular waveforms, etc.
The problem with the wrong interpretation or treating these two terms as interchangeably equivalent probably arose from the fact that when we add a constant component (the so-called offset) to the alternating current, then at a certain offset value from the alternating current we will get alternating current
