Iceberg lettuce and Lettuce

Iceberg lettuce noun - Lettuce with crisp tightly packed light-green leaves in a firm head.

Lettuce and iceberg lettuce are semantically related. In some cases you can use "Lettuce" instead a noun phrase "Iceberg lettuce".

Lettuce noun - Any of various plants of the genus Lactuca.

Iceberg lettuce and lettuce are semantically related. Sometimes you can replace phrase "Iceberg lettuce" with "Lettuce", this terms are similar.