  We provide real-space and Fock-space (FS) characterizations of ergodic,
nonergodic extended (NEE) and many-body localized (MBL) phases in an
interacting quasiperiodic system, namely generalized Aubry-Andr\'e-Harper
model, which possesses a mobility edge in the non-interacting limit. We show
that a mobility edge in the single-particle (SP) excitations survives even in
the presence of interaction in the NEE phase. In contrast, all SP excitations
get localized in the MBL phase due to the MBL proximity effect. We give
complementary insights into the distinction of the NEE states from the ergodic
and MBL states by computing local FS self-energies and decay length associated,
respectively, with the local and the non-local FS propagators. Based on a
finite-size scaling analysis of the typical local self-energy across the NEE to
ergodic transition, we show that MBL and NEE states exhibit qualitatively
similar multifractal character. However, we find that the NEE and MBL states
can be distinguished in terms of the decay of the non-local propagator in the
FS, whereas the typical local FS self-energy cannot tell them apart.
