A pentose sugar with the attached Nitrogen base is called Nucleoside.
Sugar + Nitrogen base ―→ Nucleoside
Nucleic acid molecules i.e. DNA and RNA have a Nitrogen base attached to each pentose sugar at the first carbon atom.
A nucleoside with a phosphate group is called Nucleotide.
Nucleoside + Phosphate ―→ Nucleotide
A nucleotide is a nucleoside phosphate
In a nucleotide, a phosphate group is attached to the pentose sugar at the fifth carbon.