Kettledrum and Steel drum

Kettledrum noun - A large hemispherical brass or copper percussion instrument with a drumhead that can be tuned by adjusting the tension on it.

Steel drum and kettledrum are semantically related In some cases you can replace phrase "Steel drum" with "Kettledrum", this terms are similar.

Steel drum noun - A concave percussion instrument made from the metal top of an oil drum; has an array of flattened areas that produce different tones when struck (of Caribbean origin).

Kettledrum and steel drum are semantically related in percussion instrument topic. You can use "Kettledrum" instead a noun phrase "Steel drum".