Ablative case and Oblique case

Ablative case noun - The case indicating the agent in passive sentences or the instrument or manner or place of the action described by the verb.

Oblique case and ablative case are semantically related. In some cases you can use "Oblique case" instead a noun phrase "Ablative case".

Oblique case noun - Any grammatical case other than the nominative.

Ablative case and oblique case are semantically related. Sometimes you can replace phrase "Ablative case" with "Oblique case", this phrases are similar.