The American native two species Prosopis glandulosa (Honey mesquite) and Prosopis juliflora (Mesquite) were introduced in 1878. Literature was reviewed and information were gathered both from printed material and electronic through Internet and personal experience. Morphological characteristics, Taxonomy, Common names, Botanic description, Leaves, Thorn / Spines, Flowers, Fruit and Seeds were compared and highlighted in the text for easier identification on the spot in the field. In Prosopis glandulosa leaflets are light green in colour, 6-17 pairs arranged distantly with single thorns/spines, very rarely two whereas, the leaflets of Prosopis juliflora were dark green in colour, 13-25 pairs arranged closely with a pair of thorns. The seeds oblique to longitudinal, dark brown in colour in P. glandulosa and compressed, light brown with flat cotyledons in P. juliflora.