Soul Union contracts and Twin Flame are similar but NOT the same.
The Soul Union is part of your Soul Star Family and they act as a catalyst to your awakening and expansion process. It is determined and set by you both, to help each other through a myriad of incarnations. Although, you are bonded together in Spirit, it does not necessarily reach beyond the etheric into the physical as a permanent reality in each life. It is meant to help in significant points of transition. There is great unconditional love present, however, it is not a Twin Flame.