IUI is the same as artificial insemination. IUI stands for intrauterine insemination and is the method used to deliver the sperm into the uterine environment.
If your partner has had a vasectomy he could consider a reversal of vasectomy procedure and surgical sperm retrieval with sperm freezing. If the reversal is unsuccessful the stored sperm can be used in an ICSI cycle.
Both treatments are very successful techniques to help in your situation.