No, we cannot always see the same amount of the illuminated side of the Moon from Earth. Although the Moon is tidally locked to Earth, meaning it rotates once on its axis in the same time it takes to orbit Earth, so we generally see the same lunar hemisphere (the near side), the illuminated portion of this side changes as the Moon goes through its phases. This is because only half of the Moon is always illuminated by the Sun, but from Earth, the visible illuminated fraction varies from new moon to full moon. Additionally, due to a wobbling effect called lunar libration, we can actually see slightly more than half of the Moon's surface over time, but not always the same illuminated fraction.
In summary, the phase of the Moon determines how much of the illuminated side is visible from Earth, so the amount changes continuously, although the same general face of the Moon is shown due to tidal locking.
