Block Types and Parameters are database templates. The template can be used repeatedly to form many Block Tags and Tags. Parameters are templates for both Tags and Blocks. Block Types are groups of parameters. Once a Block Tag is created, its elements have the same name as the parameters used in the Block-Type Template.
First parameters are built that reflect the elements in the Block, For example a PID control Block might have parameters for Setpoint, Measurement, Output, Auto/Manual, Remote/Local, Tuning parameters, etc. These parameters would be assembled into a block type. This block type would be used as a template to create hundreds of Controller Blocks in your project.
For Blocks to work well, the addressing in each controller must be similar with some predictable offset or pattern.