In all cases, the dictionaries answer 'what is a soulmate' by describing a person with whom we have a feeling of deep and natural affinity and compatibility. Two out of three definitions mention similar attitudes and beliefs. In other words, a spiritual relationship. There is much confusion about soul mates and twin souls. Very often these two terms have been used synonymously. They are not synonymous.
Many people believe that your twin spirit was created at the same time you were created from the same source. Your twin spirit exists apart from you yet is always connected with you on the spiritual level. The reunion of twin spirits is a very rare occurrence. Twin spirits can be male or female. They can be a man and woman who have found each other, or they can be of the same sex.
Kindred Spirits is a hard term to define. There is no real description for it; just like soulmate, it has many meanings. The most common meaning for it is to have a bond with someone whom you share the same interests, personality, character, etc. The probable difference between soulmate and kindred spirit is that as we go through life we do come across many people who resemble our own nature.