What is the difference between life composed of RNA and life composed of DNA

How would they look different?

No difference. All known forms of life have both.

DNA (deoxyribonucleic acid) is double stranded (double helix) and the two strands are complementary to each other (G with C and A with T). DNA codes for everything, sometimes directly, but often indirectly. It even codes for RNA.

RNA (ribonucleic acid) is single stranded. RNA is made up of base pairs (so is DNA). 3 base pairs comprise a codon, which codes for different amino acids, which make up proteins. So with the help of ribosomes, RNA makes proteins. Also there are three types of RNA, rRNA (ribosomal RNA) mRNA (messenger RNA) and tRNA (transfer RNA) which are complementary to each other when making a protein, this time however the A is not complementary with T, but instead it is complementary with U.

Hope this helps!

Half of DNA is RNA with only one of the four amino acids slightly different, and the difference is between uracil and guanine is probably one hydrogen or oxygen atom. Life cant exist without BOTH RNA AND DNA, because RNA builds proteins. A virus is essentially DNA with a protein coat.