Consumer versus Professional Film
Film has a tendency to suffer color balance shifts as it ages. The aging usually takes place if the film is stored at room temperature. The actual science is above my head, but thankfully, someone understands it and made provisions for it.
Consumer grade film is manufactured with the understanding that the average consumer will likely buy more than one roll of film, and that the film will either be left on a shelf, or in the camera for a long time before being processed. Because of this, the film is packaged slightly before the color balance is optimal.
Professional grade film on the other hand, is designed with the following in mind: a professional will usually buy a lot of film, use it quickly, and bring it in for processing shortly after its purchase. Therefore, it is manufactured so that it is at its optimal color balance when it is packaged. Because it is at its best when purchased, if the film will remain unused for a prolonged period of time, it should be refrigerated as per the manufacturer's instructions to prevent the color from shifting.
So if you are purchasing film that you will be using in the very near future, and you intend to finish the roll and bring it in for processing shortly thereafter, you might consider spending the extra on professional grade film.