Difference between SHACL `RULE` and SPARQL `CONSTRUCT`?

[ajnelson-nist]

I think the Inference document would benefit from a section explaining the difference between SHACL's RULE and SPARQL's CONSTRUCT. E.g.,

• What are the differences in grammar, if any aside from RULE and CONSTRUCT terminals?
• How do Rules interact with sh:SPARQLRule from SHACL-AF? Quoting @afs from this comment:

  It might be nice to include a section somewhere in SHACL 1.2 - in rules or in a note "migrating form SHACL-AF").
  SHACL triple rules and SPARQL Rules can marked as legacy. For backwards compatibility, they will need to run separately else new RULEs may interfere with legacy CONSTRUCT.