Difference between Obligatory and De Rigueur

OBLIGATORY vs DE RIGUEUR: NOUN

Strictly required, as by etiquette, usage, rule, etc.; essential; imperative: as, full dress is de rigueur.

Requiring a matter or obligation.
Imposing obligation, morally or legally; binding: an obligatory promise.
Binding in law or conscience; imposing duty or obligation; requiring performance or forbearance of some act; -- often followed by on or upon.
Obligate.
Required as part of a routine course of action or cultural expectation; predictable.
Of the nature of an obligation; compulsory.
Morally or legally constraining or binding
Required by obligation or compulsion or convention

Imposing obligation; binding in law or conscience; imposing duty; requiring performance of or forbearance from some act: followed by on before the person, formerly by to.

According to strictness (of etiquette, rule, or the like); obligatory; strictly required.

Statutory, Minimum, Requirement, Mandated, Obliged, Incumbent on, Imposed, Bounden, Indispensable, Necessary, Prerequisite, Required, De rigueur, Mandatory, Compulsory

Chic, Fad, Prevalent, Modish, Infra dig, Voguish, Trendy, Norm, Au courant, Passe, Vogue, Ubiquitous, Fashionable, Commonplace, Obligatory

Statutory, Minimum, Requirement, Mandated, Obliged, Incumbent on, Imposed, Bounden, Indispensable, Necessary, Prerequisite, Required, De rigueur, Mandatory, Compulsory

Chic, Fad, Prevalent, Modish, Infra dig, Voguish, Trendy, Norm, Au courant, Passe, Vogue, Ubiquitous, Fashionable, Commonplace, Obligatory

But it is not obligatory in this case.
Obligatory use of local labor, plant and material.
APA the cover page is not always obligatory.
Obligatory committees needed to do businessaudit, budget etcvi.
Telugu Meaning of Obligatory or Meaning of Obligatory in Telugu.
This Act applies to obligatory insurance contracts with the specifications arising from the Act which establishes obligatory insurance.
The state obligatory standards of relevant levels of education are obligatory for all educational organizations irrespective of their form of ownership, types and kinds.
If one is performing dry ablution for an obligatory prayer, one must intend its being obligatory, though need not specify whether.
It shows that circumcision was obligatory upon him and therefore obligatory on all men.
But I feel this obligatory part is looking a lot less obligatory.

House of El and the cape is de rigueur for working appearances.
Responding to charges of child molestation by discrediting victims was de rigueur.
That kind of post used to be de rigueur in Rolling Teenpop.
Specifically, Heuer Autavia and Carrera chronographs were de rigueur among drivers.
At Knopf under Sonny Mehta, it became positively de rigueur.
Botox is already de rigueur for those aging boomer babe.
For new grads, amassing certifications has almost become de rigueur.
Float tubes, small skiffs and canoes are de rigueur.
Before the age of recycling, salvage was de rigueur.
Give it up guys, its now de rigueur.