1) the tissue consists of thin-walled living cells. 
2) it is distributed in almost all the parts of the plant body . 
3) the living cells of parenchyma assimilate and store food .They also store waste products. 
4) It contain dense cytoplasm. 
5) Intercellular spaces may or may not be present. 

1)the tissue consists of cells having localized thickening in their cell walls 
2)it occurs mostly in the aerial parts of the plants restricted to the other layers 
3)collenchyma is the chief mechanical tissue of the young parts of the plant particularly in the young dicotyledonous stems. in parenchyma cells are thin walled having intercellular spaces.and in collenchyma cells are thick walled having the absence of intercellular spaces. 
4) It contain cellulose and pectin. 
5) Intercellular spaces are totally absent. 
6) Collenchyma is present in peripheral regions.