Basically are the same thing. Originally the researchers and taxonomists though that all the arbuscular mycorrhizal fungi forms vesicles inside roots, until some years ago was observed that Gigaspora and Scutellospora do not forming such structures, if I remember well the clasification system for AM fungi proposed by Dr. Joe Morton, principal curator of INVAM in 1990 where he proposed the orders Glomineae and Gigasporineae explain very well that. Then, the most general terminology that close all that fungi in a common pattern was the term arbuscular and is the predominating form used at present. Best regards, Eduardo
Mycorrhizal associations produced by Glomeromycotan fungi are known as arbuscular mycorrhizas, or vesicular-arbuscular mycorrhizas, formerly also endomycorrhizas, or endotrophic mycorrhizas and are abbreviated as VAM here. There is disagreement about whether arbuscular mycorrhizas or vesicular-arbuscular mycorrhizas is the most appropriate name to, because some fungi do not produce vesicles, but arbuscules are not consistently used to identify associations, i.e. they are absent in mycoheterotrophs and older roots. These associations involve primitive fungi in the Glomeromycota and a wide diversity of plants.