As already stated, the similarities are greatest towards the start of the series. The plots are as follows:
Hero (and friends) living in rural utopia. Along comes a wise old man (woman), with threats of doom if the hero does not come with them on a journey. The threat, of course, is an evil creature who wishes to destroy the world and then rule over it. This evil creature was defeated a few thousand years and exiled but now he's back for revenge. The hero and a few friends leave on a quest towards wisdom, but find that their roles are much bigger.
But other than this (and the obvious similarities between the different species/characters/places), there are few similarities and many dissimilarities.
- Good vs. evil:JRRT takes a very black-and-white approach to good and evil. Robert Jordan has a much more grayer approach.
- World-building:JRRT does impressive world building, but I think it pales in comparison to Jordan's. JRRT is able to think of places and their histories, but really is not able to make up cultures. Jordan, on the other hand, makes up different cultures as well.
- Status-For JRRT, blood is everything. Royals are a class apart. Women are little more than damsels-in-distress. Everybody seems to accept their status in life. For Jordan, bloodlines are important, but so is ability. Women are important players in the game. Everybody is always struggling to maintain/improve their status.
- Character depth-In LoTR, characters are usually quite abstract or one-dimensional. Once you read about a character, there shall be no surprise regarding his decision. They are either good or bad. RJ, on the other hand, revels in surprises when it comes to characters. Similarly, love is so abstract in LoTR, but more earthly in WoT.
So though the plots seem to be very similar in LoTR and WoT, the writing style is more complex in WoT (probably because it was written 40-50 years later and had more diverse writings to draw upon for style.)