When we make a comparison we need to know what we are comparing. Often this is easy:
Some languages Subject seem harder comparative adjective than others pronoun (head of the prepositional phrase). (Sorace 2023)
In one short sentence we know that the comparison is between "some languages" and "others" (other languages) in terms of how hard they are to learn or understand. The comparison is made explicit by the use of the preposition "than". But in writing, especially academic writing, the comparison may not be so clear, especially if the sentence is taken out of context.
For example, what is being compared here?
It was warmer adjective, more acidic adjective and rich in iron. (Jordan 2019)
The problem is we don't know what "It" refers to. And even if we did we might not know what "it" is being compared with. In fact, it is the ocean today compared with an ocean 4.5 billion years ago. Nevertheless, it is often important to make comparisons explicit. One way is to use a comparative phrase or clause following the comparative adjective, as in the first example above, which is a comparative phrase (a prepositional phrase).
They’re a lot cheaper comparative adjective than a decent telescope comparative phrase (prepositional phrase), too. (Laycock 2019)
"They" refers to binoculars. The comparative phrase is a prepositional phrase ("than a decent telescope").
The Great Red Spot is a storm noun bigger comparative adjective (object predicative) than earth comparative phrase (prepositional phrase). (Kedziora-Chudczer 2022)
The comparative phrase is a prepositional phrase ("than earth").
But gills and lungs are more degree adverb similar predicative adjective than than you might think comparative clause . (Brown 2021)
The comparative is a clause "than you might think".
In the same way, a teenager’s brain is less degree adverb mature predicative adjective than an adult brain comparative phrase (prepositional phrase). (Wilson 2019)
The comparative phrase is a prepositional phrase ("than an adult brain").
Other degree complements use comparison to indicate other meanings such as adequacy (enough), excess (too), equivalence (as .. as), and result (so ... that).
"too" denotes excess.
This structure denotes equivalence (to the same degree), or lack of equivalence.