RNA vs soluble RNA

RNA and soluble RNA both are nouns.

Word	Noun	Adjective	Verb	Adverb
RNA	Yes	No	No	No
soluble RNA	Yes	No	No	No

As nouns, soluble RNA is a hyponym of RNA; that is, soluble RNA is a word with a more specific, narrower meaning than RNA:

RNA: (biochemistry) a long linear polymer of nucleotides found in the nucleus but mainly in the cytoplasm of a cell where it is associated with microsomes; it transmits genetic information from DNA to the cytoplasm and controls certain chemical processes in the cell
soluble RNA: RNA molecules present in the cell (in at least 20 varieties, each variety capable of combining with a specific amino acid) that attach the correct amino acid to the protein chain that is being synthesized at the ribosome of the cell (according to directions coded in the mRNA)

RNA (noun)	soluble RNA (noun)
(biochemistry) a long linear polymer of nucleotides found in the nucleus but mainly in the cytoplasm of a cell where it is associated with microsomes; it transmits genetic information from DNA to the cytoplasm and controls certain chemical processes in the cell	RNA molecules present in the cell (in at least 20 varieties, each variety capable of combining with a specific amino acid) that attach the correct amino acid to the protein chain that is being synthesized at the ribosome of the cell (according to directions coded in the mRNA)