Short answer. Basically the same. Rule 123, Section 1 provides that the procedure in Metropolitan, Municipal, and Municipal Circuit Trial Courts is the same as in Regional Trial Courts, except where a particular provision applies only to one or the other, and except in criminal cases governed by the Revised Rule on Summary Procedure.
What the law says
The procedure to be observed in the Metropolitan Trial Courts, Municipal Trial Courts and Municipal Circuit Trial Courts shall be the same as in the Regional Trial Courts, except where a particular provision applies only to either of said courts and in criminal cases governed by the Revised Rule on Summary Procedure.
Rule 123, Section 1 — Uniform Procedure. Read the full provision →
One baseline procedure across trial court levels
Section 1 establishes uniformity as the default: first-level courts — Metropolitan, Municipal, and Municipal Circuit Trial Courts — follow the same procedure as Regional Trial Courts. Litigants do not need to learn an entirely separate procedural system depending on which trial court level their case is filed in. This matters for anyone appearing before a first-level court without necessarily having separate counsel familiar with a wholly distinct set of procedural rules.
Provisions specific to one court level
That uniformity has a built-in exception for particular provisions that, by their own terms, apply only to either the first-level courts or the Regional Trial Courts. Where a specific rule is written to apply to just one level, that specific provision controls over the general rule of sameness. Such level-specific provisions exist throughout the rules, and where they apply, the general default of sameness in Section 1 simply steps aside.
The bigger carve-out: Summary Procedure
The more significant exception is for criminal cases governed by the Revised Rule on Summary Procedure, which covers offenses like certain traffic and other minor violations with penalties not exceeding limits set by that rule. Those cases follow the streamlined Summary Procedure process instead of the ordinary criminal procedure Rule 123 otherwise imports from the Regional Trial Courts, since Summary Procedure is built for speed rather than a full-length trial.
Why this design makes sense for first-level courts
Importing the Regional Trial Court procedure as the default, rather than drafting a wholly separate rulebook for first-level courts, keeps the overall system easier to learn and apply consistently, since practitioners and litigants encounter largely the same procedural rules whichever trial court their case happens to land in. The narrow carve-outs for level-specific provisions and for Summary Procedure cases let the Rules still account for the practical differences between a case that needs a full trial and one that calls for a faster, simplified resolution.