sanfx
what is difference between delete and blast SOP

Blast is designed to remove geometry that you select interactively in the viewport, as opposed to Delete which is a more procedural tool.

In addition to simply deleting unwanted parts of a model, this operator is useful for culling primitives from very dense geometry to speed up cooking of nodes downstream.

This operation can also delete profile groups (for example, 0.5 1.2-3.9) and mixed groups (for example, 0 0.5 4-12 1.2-3.9). It can also delete entire paste hierarchies or pasted surfaces, causing the remaining hierarchy to update. By deleting the root of a paste hierarchy, the whole hierarchy becomes undone.