Until 2009 there was a flag which was very similar to the current flag of Bedfordshire. This was the flag of the county council and was often mis-sold as a flag to represent Bedfordshire itself.
The two designs are very similar as the true Bedfordshire flag is based on the old council design. One obvious difference is the design of the scallops (shells). This is down to the flag makers themselves. Prior to the flag being included in the Flag Institute registry there were several variations of shell design, only now has this detail been nailed down officially.
The main difference, however, between the county and council flags is the arrangement of the wavy lines that run horizontal across middle of the flag. On the old council design these went white-blue-white-blue on both sides of the flag. The officially recognised design registered with the flag institute has this order reversed on the left hand side. This is the correct version of the county flag.
The reason for this is to obey “the rule of tincture” a heraldic design principal which means that white and yellow should not be seen next to each other. The reversing of the colours makes this possible.
Flying older versions of the council flag is not wrong but you will be flying the flag of the old administrative body and not Bedfordshire as a whole.