Memory bandwidth is how much information it can move in 1 second.
Txture fill rate is how fast it can fill textures. and image is a bunch of polygons one your screen and the GPU fills them with textures, Like skin, clothes, bark, leaf... so its how fast it can fill these.
graphic performance mainly depends on the core graphics processor itself probably followed next by memory bandwidth. memory size only comes into play at higher resolutions or 3d gaming and 2gb is usually fine for normal 1080 gaming.