Difference between Spine-Leaf and Collapsed Core?

This is probably a simple question, but my googling so far is only showing differences between Spine-leaf and the traditional 3-tier architecture.

Let's say you have 2 stacked Layer-3 core switches. All ToR and Access switches have an uplink to both core switches. The redundant uplinks ports are all configured as LAGs.

Is this considered spine-leaf or collapsed core?

Spine-leaf is not supposed to interconnect the spine switches, right? Does stacking count as interconnecting?

Is spanning-tree a requirement for it to be collapsed core?

Thanks guys!