The fraction 16/4 leads to 4 when division is applied. The number 4 is a whole number and whole numbers are classified as integers. The decimal 12.5 is the improper fraction 125/10. The fraction 125/10 leads to a decinal number which is not a whole number. In conclusion, 16/4 is the whole number 4 while 12.5 is a decimal number and decimal numbers are not integers.