Types of living organ donation

    Some might think that by registering themselves as organ donors means that the donation will be made after they have died. It is important to be aware that organ and tissue donation can be done while the donor is alive. Living donations happen among close relations or between unknown people.

    The most commonly transplanted organ from living donors are kidneys. The whole kidney can be removed and transplanted providing the remaining kidney of the donor is functioning well. A part of organs like liver, lung, intestine or pancreas can be removed and transplanted from a living donor.

Living donor transplants can be categorized into the following:
1. Directed donation
2. Non-directed donation
3. Paired donation

Directed donation
The donor addresses a specific person to receive the transplant.
The donor might have blood connection with the recipient, like siblings.
Also, the donor might not have blood connection with the recipient but knows the recipient is in need of an organ transplant, for example a good friend who is suffering from chronic kidney failure.

Non-directed donation
The donor does not address a specific person to receive the transplant.
The donor might or might not have the chance to meet the recipient.
The organ donation is arranged according to the medical compatibility of the organ with the health condition of the patient in need.

Paired donation
The donor is unable to donate due to incompatibility with the recipient, but is then matched with another donor and recipient with similar case. 
It is best to understand it with illustration.

Source:
https://www.unos.org/donation/living-donation/
https://www.hta.gov.uk/types-living-organ-donation
http://slutransplant.com/slu-center-for-abdominal-transplantation-joins-kidney-paired-donation-program/