In terms of comparison, Thai rice tends to be of higher quality and subject to fewer variations in availability. Cambodian rice is just starting to be of sufficient production to be available for export. Vietnamese rice is generally not as high of quality as Thai rice. This is due to a large extent because of lesser care in handling after harvest. Also, because Vietnam is more subject to Typhoons and floods, these calamities sometimes affect availability of certain rice types.
Price though is often times quite favorable.
White rice means rice that is obtained by removing bran from cargo non-glutinous rice. Cargo rice is rice that is dehusked only. White glutinous rice is rice that is obtained by removing the bran from cargo glutinous rice. Parboiled rice is popular in certain parts of Africa. It is rice that has been parboiled and has its bran removed.