Similarities between Mendeleev's periodic and Modern periodic table: Elements are arranged in groups and periods. Elements with similar properties are placed in the same group. Metals and non-metals are placed separately.
The main differences are: Mendeleev's periodic table is based on atomic mass. Modern periodic table is based on atomic number.
Mendaleev's periodic table contains about 66 elements. In modern 118 elements.
In Mendaleev's periodic table no place for nobel gases. But in modern 18 group is for nobel gas.