Animal cells do not have a cell wall but only the cell membrane. In plant cells, a cell wall is located outside the cell membrane, which gives the cell, its structure and strength.
When a cell is kept in a hypotonic medium, the cells take up water from external medium and swell up.
In plant cells, the cell membrane creates a pressure against the cell wall, which exerts an equal pressure against the swollen cell but do not burst.
Because of the strong cell walls, plant cells can withstand much greater pressure of internal swelling of cell than the animal cells.