Is it true? And does it apply to all Enlighten Brick products?
Enlighten Brick is a Chinese LEGO knock-off brand.
A lot of, if-not most of, the sets the produce are basically copies of existing LEGO sets, either current ones or popular retired ones.
From their website though, they do appear to have some of their own designs.
Edit by Phil B: Word of Warning: By buying counterfeited sets (such as these Enlighten Bricks copies of LEGO sets) you are sponsoring illegal activities, which if not stopped might ultimately cause irreversible damage to the LEGO brand and the high quality, original sets it provides. Enlighten can offer sets for less than what the equivalent LEGO set would cost purely because instead of investing in R&D they have stolen LEGO's Intellectual Property.
Lepin is a Chinese brand that exclusively clones LEGO sets or user-created MOCS.
Most other Chinese brands sell (mostly) sets based on original designs. Englighten is one such brand.
For example, Enlighten sells several military themed sets, which is a theme LEGO has always avoided :
It also has sets in various other themes that are totally original designs :
It does appear, however, that at least some of their designs are in fact copies of LEGO designs. As you pointed out yourself, the Enlighten Brick Black Pearl set is clearly a copy of LEGO set 6285 or 10040.
I've seen many Enlighten sets, however, and this is the first one I encounter that is actually based on a LEGO set.
The Enlighten sets from the "combat zones" old series are copied from the LEGO Indiana Jones sets. For example, the amphibian vehicle is a copy of the set number 7625 River Chase.