What is the difference between Mendeleev's Periodic Table and other chemists' periodic table?

Before the modern periodic table, many people had attempted to classify the elements so that an organised arrangement in which elements with similar chemical properties are arranged together could be obatined. Notable among them were Dobereiner's triads, in which the elements showing similar chemical properties were arranged in sets of three. Also, there was Newlands law of octaves, according to which if elements are arranged in the order of increasing atomic masses, then the properties of every eighth element are similar to that of the first. 

The Mendeleev's classification of elements was also based upon the atomic masses of elements. However, Mendeleev classified the elements into group and periods, which has also been retained in the modern periodic table. Also, Mendeleev's classification of elements contained gaps for those elements which were not discovered at that time. No such gaps were there in the Dobereiner's triads or Newlands' classification of elements. 

The modern periodic table classifies the elements according to their atomic numbers and not their atomic masses. This is the major difference between Mendeleev's classification (along with other classifications) and the modern periodic table. Moreover, the modern periodic table also overcomes the shortcomings of placement of isotopes, which could not be addressed by the Medeleev's classification of elements.