By using the notion of a d-embedding $$\Gamma $$
Γ
of a (canonical) subgeometry $$\Sigma $$
Σ
and of exterior sets with respect to the h-secant variety $$\Omega _{h}({\mathcal {A}})$$
Ω
h
(
A
)
of a subset $${\mathcal {A}}$$
A
, $$ 0 \le h \le n-1$$
0
≤
h
≤
n
-
1
, in the finite projective space $${\textrm{PG}}(n-1,q^n)$$
PG
(
n
-
1
,
q
n
)
, $$n \ge 3$$
n
≥
3
, in this article we construct a class of non-linear (n, n, q; d)-MRD codes for any $$ 2 \le d \le n-1$$
2
≤
d
≤
n
-
1
. A code of this class $${\mathcal {C}}_{\sigma ,T}$$
C
σ
,
T
, where $$1\in T \subseteq {\mathbb {F}}_q^*$$
1
∈
T
⊆
F
q
∗
and $$\sigma $$
σ
is a generator of $$\textrm{Gal}({\mathbb {F}}_{q^n}|{\mathbb {F}}_q)$$
Gal
(
F
q
n
|
F
q
)
, arises from a cone of $${\textrm{PG}}(n-1,q^n)$$
PG
(
n
-
1
,
q
n
)
with vertex an $$(n-d-2)$$
(
n
-
d
-
2
)
-dimensional subspace over a maximum exterior set $${\mathcal {E}}$$
E
with respect to $$\Omega _{d-2}(\Gamma )$$
Ω
d
-
2
(
Γ
)
. We prove that the codes introduced in Cossidente et al (Des Codes Cryptogr 79:597–609, 2016), Donati and Durante (Des Codes Cryptogr 86:1175–1184, 2018), Durante and Siciliano (Electron J Comb, 2017) are suitable punctured ones of $${\mathcal {C}}_{\sigma ,T}$$
C
σ
,
T
and we solve completely the inequivalence issue for this class showing that $${\mathcal {C}}_{\sigma ,T}$$
C
σ
,
T
is neither equivalent nor adjointly equivalent to the non-linear MRD codes $${\mathcal {C}}_{n,k,\sigma ,I}$$
C
n
,
k
,
σ
,
I
, $$I \subseteq {\mathbb {F}}_q$$
I
⊆
F
q
, obtained in Otal and Özbudak (Finite Fields Appl 50:293–303, 2018).