Are the iliac crest and spine same thing?

The iliac crest and the iliac spine are not the same thing.

The iliac crest is the upper border of the ilium, the largest of the three bones that form the pelvis. It is a curved ridge that runs from the anterior superior iliac spine to the posterior superior iliac spine.

The iliac spine is a bony projection on the ilium. There are two iliac spines: the anterior superior iliac spine and the posterior superior iliac spine. The anterior superior iliac spine is located at the front of the pelvis, just above the hip bone. The posterior superior iliac spine is located at the back of the pelvis, just above the sacrum.