Nucleoside is nucleotide without a phosphate group. That is something we say to understand and correlate nucleotide and nucleoside. But if followed Terminology by IUPAC a nucleotide should contain only one phosphate group, not more than that. Though NTP is a type of nucleotide, however, for the sake of technical terminology, nucleotides are given classifications as nucleosides with a suffix describing the number of phosphates present in a specific unit. For example, if a nucleotide has one phosphate, it is a nucleoside monophosphate (NMP). If the nucleotide has two phosphates, then it is called a nucleoside diphosphate (NDP), and for three, it is a nucleoside triphosphate (NTP). So you can say NTP as nucleotide diphosphate, but considering the fact that nomenclature also indicate the chemical property of the compound, it would not be right.