The BR40 and R40 designations (with or without the dash) are very often used interchangeably. For example, GE Lighting has both a bulb called GE Heat Lamp Saf-T-Gard® R40
and a bulb called GE Plant Light BR40
both having the same reflector type design (hence the "R"), same reflector diameter - 5" ("40" stands for 40 x 1/8" - it is how the diameter is specified) and same MOL (Minimum Overall Length) - 6.56" although they do look slightly different in shape - BR40 is slimmer toward the base.
Unfortunately, with reflectors you also need to specify the MOL - minimum overall length. For BR40/R40 I've seen it anywhere between 5.25" to 6.6". LED bulbs tend to be on the shorter side, incandescent and CFLs tend to be longer.
If you are replacing a 6.6" xR40 reflector bulb, you will be safe ordering any xR40 bulb. If you are replacing bulbs that were shorter than 6.6", you need to check their length before ordering.  Â