Basic
Anyone can offer or receive a basic friendshape. It can be offered to anyone you have actually met. You might not know much about each other or have spent much time with each other, but you want to establish a significant connection. I suppose this mainly a way to see what this person is up to, with minimal ways for interaction.
Significant
If you have spent a significant amount of time with someone on a personal basis, even several hours, you have already made a lasting commitment to them. Those you care about, think about, but have little or no contact with. Acquaintances with whom you share something, but with whom your care and commitment is minimal.
Major
Throughout the whole of life, regardless of changing circumstances, we share each other’s failures and success, struggles and achievements.