Are si units the same as metric units?
In general, yes.
Development of the metric system began in the 1800's. The effort that resulted in the International System of Units (SI) began in the 1960's. SI is an organization of what is referred to as the metric system. As an example of why it was considered that the metric system might benefit from organization:
In the metric system, volume can be given in
#cm^3, liters, or m^3#. In SI, #m^3#is the only proper unit to be used for volume.
So SI could be considered an organization or standardization of the metric system. But the simple answer to your simple question, is yes.
I hope this helps,