Major differences to consider before deciding which to use:
Polycrylic is water based.
Polyurethane is considered more durable.
Polycrylic dries faster.
Polyurethane has greater water resistance.
Polycrylic is easier to clean.
Polycrylic tends to dry to a clear or slightly milky hue.
Polyurethane tends to dry with a slight yellowish tint.