I found this answer "online" and was surprised. Take it for what it's worth.
Insignia is Best Buys in-store brand. Best Buy actually contracts different manufacturers to produce the different products sold under this name. Even narrowing the scope down to Televisions, some might be produced by one company, others by a different company.
Insignia is made up of all LG parts. best buy purchases them from LG, everything inside of an Insignia TV is "last years" LG internals.