ما معنى Strong and weak orders of convergence, Milstein scheme؟

A scheme with step $h$ has strong order of convergence $\gamma$ if $\E|X_T^h - X_T| \le Ch^\gamma$, and weak order of convergence $\beta$ if $|\E g(X_T^h) - \E g(X_T)| \le Ch^\beta$ for smooth $g$. The Milstein scheme for $dX = a(X)\,dt + b(X)\,dW$ adds to the Euler–Maruyama step the term $\frac12b(X)b'(X)((\Delta W)^2 - h)$.