There are two main varieties of Acacia differing in habitus, namely Senegalia senegal var. senegal (shrub, small tree) and Senegalia senegal var. leiorhachis (slender tree).
All photos shown on this page are under the copyright of Mr. Hauke-Peter Vehrs, Halle, Germany.
The first three pictures show A. senegal var. senegal; pictures 4-6 show A. senegal var. leiorhachis.