I'm 95% certain, especially from your answer (which you could change to a comment) that your advisor meant 2/2.* A measure of 2/2 and a measure of 4/4 could look identical; both might have, for instance, 4 quarter notes in them.
So what's the difference? That has been covered more than once here. My favorite half-joking explanation is "the only difference is how the conductor waves their arms." In a 4/4 measure, she would move the baton in 4 motions. If the same measure were marked 2/2**, the notes would be heard at exactly the same rate, but she would make only two motions, half the speed of her 4/4 conducting.
If there's no conductor, just yourself the performer, the difference is in how you feel and think of the beat, and hopefully how that affects your playing in a way that can be heard. In 4/4, you think of four distinct beats. It might create a "march" feeling—in fact, try physically marching in place while playing. But in 2/2, each pair of quarter notes becomes only half of a larger beat. Keep your musical notes going at the same speed, but march at half the speed you were going, stepping only twice per bar. Hopefully this also affects the way you musically emphasize the notes, putting less emphasis on the second and fourth quarter notes, as you think of them as just the latter halves of two big beats.
This is often very good advice. Except in genres that strongly emphasize the beat (march, polka, reggae, disco), it's often musically beneficial to break down emphases that separate beats and instead unite notes into longer phrases.
* For one thing, 2/4 would have the opposite effect; you'd start emphasizing even more beats as what was the middle of the measure would become a downbeat.
** (Assuming that the half note beat for the 2/2 is half the tempo of the quarter note beat for the 4/4)