I think I have not understood clearly the difference between dimension and shape. I want to construct a vector remembering recurrence of the type :

({{f[0]},{g[0]}}) = ({{1},{1}})

{{f[n]},{g[n]}}) := ({{f[n]},{g[n]}}) = ({{0.2 f[n - 1] + g[n - 1] + 1}, { f[n - 1] + 0.2 g[n - 1] + 1}} )

gives the following error

SetDelayed::shape: Lists {{f[n]},{g[n]}} and {{f[n]},{g[n]}}={{0.2 f[n-1]+g[n-1]+1},{f[n-1]+0.2 g[n-1]+1}} are not the same shape.

but according to Dimensions they are both equal to

{2, 1}

So what is the difference between shape and dimensions