We study the equivalences and implications between linear (or homogeneous) nth order fractional differential equations (FDEs) integral in spaces L1(a,b) C[a,b] when n≥ 2. establish equivalence of IVP FDE subject to initial condition u(i)(a)=ui for i {0,1,...,n-1} n≥2. The difficulty is that known conditions such first FDEs are not sufficient with In this article we provide additional ensure par...