Is self employment tax at 15.3% rate same as SS tax? I'm a dependent with only $715 on 1099- MISC as independent contractor. I looked at Schedule SE & Form 8919

Self-employment tax has two parts to it - social security tax (12.4%) and medicare tax (2.9%).  When you have a 1099-MISC, you are responsible for paying the full amount of self employment tax.  When you have a W2 job, you and your employer split the cost of SE tax, so you each pay 7.65%.