What are differences of the implicit ID and the explicit ID of a JSON type in JSON Schema?

If a JSON type is defined under a "definitions" property, it could have two identifications:

1. Implicit identification: The implicit identification of a JSON type is an internal bookmark in the form of "#/definitions/xxx", where "xxx" is the type name. For example, the JSON type in the following JSON schema has an implicit identification of "#/definitions/rating":

{   
  "definitions": {
    "rating": {
      "type": "integer",
    }
  },
  ...
}

2. Explicit identification: The explicit identification of a JSON type is the identification assigned by the "$id" property. For example, the JSON type in the following JSON schema has an explicit identification of "#point":

{   
  "definitions": {
    "rating": {
    "$id": "#point",
      "type": "integer",
    }
  },
  ...
}

Following JSON schema shows a JSON type called "rating" that can be referenced internally with two identifications: "#/definitions/rating" and "#point":

{
  "definitions": {
    "rating": {
      "$id": "#point",
      "type": "integer",
      "minimum": 0,
      "maximum": 5
    }
  },
  "type": "object",
  "properties": {
    "clarity": {
      "$ref": "#/definitions/rating"
    },
    "efficiency": {
      "$ref": "#point"        
    }
  }
}

⇒ JSON Type Metadata

⇐ JSON Type Unique Identifications

⇑ Introduction of JSON Schema

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