How many times are the words "القبور" (graves) and "الأجداث" (tombs) repeated in the Holy Quran, what is the difference between them, and why did the Holy Quran use each of them in different contexts?

The apparent understanding from the words of the exegetes and linguists is that the two words "al-ajdath" (الأجداث) and "al-qubur" (القبور) share the same meaning, and perhaps the variation in wording is for the sake of diversification. The word "al-ajdath" appeared three times in the Quran, while the word "al-qubur" appeared five times.