In case it wasn't clear in my recent review, Ju-On is the original Japanese version of the Grudge, and since I played through the game, I might as well review the movies a little bit too. This isn't going to be an official review for these films, but I thought it might be interesting to compare the two.
For starters, Ju-On has four movies, and the Grudge has three, the third of which was not based from the Ju-On series. And trust me, it took me forever to figure out the parallels between the movies. It didn't help that the Ju-On films were not labelled from one to four. Instead they were titled Ju-On the Curse 1-2, and Ju-On the Grudge 1-2. Keep in mind that I am reviewing seven movies, some of which have very similar themes. I'll try and not make it too confusing.
For those who did not follow my Grudge reviews, the plot was pretty simple-a woman (Kayako) was murdered by her husband (Takeo) because she had a crush on her son's teacher. Her son (Toshibo) was also murdered. After their death, a curse was born. Anyone who entered the house would shortly die, followed by anyone connected with the victim. Personally, I think that is a little unfair, but what do I know? I'm not a vengeful spirit.
In Ju-On the Curse 1, the backstory of Kayako and Toshibo is explored, which is later copied onto the Grudge 1. In this movie there are only a few subtle differences between the two movies, such as the fact that Takeo did not commit suicide in the Grudge and was in fact murdered by Kayako later. The death of the school teacher was also done differently and I have to say that I like the Ju-On version a little more. There is also a subplot involving another family who moves in and later dies.
Out of all the movies in the series, Ju-on the Curse 2 is the most boring to watch, just because almost half the movie literally repeats the one before. There is however a subplot involving a psychic who is the sister of a real estate agent trying to sell the house. I actually liked the psychic as she comes up with an interesting way of warning people not to enter the house. Unfortunately, this subplot ended way too fast for my liking. There are also a few scenes in this movie that are copied into the start of Grudge 2, such as a random wife killing her husband with a frying pan.
Ju-on the Grudge 1 (sigh, and it took me forever to realize this was the third movie in the series) again follows closely to the Grudge 1, where a social worker comes into the house and discovers what happened to Kayako and Toshibo. Again, there are subtle differences in this movie. For example, in the Grudge 1, the protagonist tries to burn the house down at the end. In Ju-On the Grudge 1, the protagonist defeats Kayako in an elaborate game of peek-a-bo (don't ask me how that worked, I really can't explain it).
Overall though, these two movies are the most similar. It should be noted that the main plot of the Grudge 2 involving the sister of the social worker is not in the Ju-On series at all.
From this point on, the movies are entirely different and bare no similarity to each other. The Grudge 3 was created without any scenes from the Ju-On series, and it was only direct-to-DVD. Takashi Shimizu, who directed both the first two Grudge movies and the Ju-On films, couldn't come up with any new ideas and decided not to direct a third. It also wasn't filmed in Tokyo and the actors who played Kayako and Toshibo were also replaced. Naturally, it sucked. The set design looked awful, the ghosts were laughable, and it wasn't terrifying at all.
....uh huh, keep trying to be scary there, Kayako.
The same couldn't be said for Ju-On the Grudge 2, which to me was just as scary (if not more) as the other films in the series. In this film, a pregnant actress ends up in a car crash (caused by Toshibo) yet her baby remains fine. Primarily because Kayako is now possessing it. I won't spoil the ending, but it does add a new dimension to Kayako's character. There is also a sub-plot involving more people dying, but how they die is extremely creepy. I definitely recommend this film to any Grudge fans.
I've covered all the movies, but stick around for part 2, where I talk more about Kayako in depth!