Do you think the microspores and pollen grains are the same structure . If they are different then what is the basic difference between them ?

Explanation

Microspores and pollen grain are not the same structures . Initially the diploid microspore mother cell divides by meiosis to form four haploid microspores which are arranged in tetrads. Each microspore has single haploid nucleus. Then the nucleus of microspore divides mitotically so that the two haploid nuclei are formed inside the spore. The entire cell becomes bicellular by developing a separating wall. Now the spore is tow celled- one large tube cell and othe smaller generative cell. This structure is regarded as young male gametophyte and called as pollen grain. Pollination takes place at this two-celled stage.