Motor Power and Performance
The 1000W versus 1100W gap is real but small; both motors handled frozen fruit and dense shakes without stalling.
Blades and Total Crushing Technology
Both pitchers use the same Total Crushing blades, and side by side both crushed ice to fine snow in seconds; the cup blades pull frozen food down even better.
Pitcher Size and Batch Capacity
The pitchers are identical: 72 ounces, 64 ounces max liquid.
Ease of Use and Cleaning
Neither machine is hard to clean when rinsed right away; a soapy-water spin cycle cleaned both in seconds. The BL610's tall jar felt awkward in a small sink, and the BL660's extra parts clutter the rack.
Noise Level
The BL610 is the louder of the two, audible from the next room, while the BL660 is still noisy but blends so fast the racket is short.
Price and Value
The BL610 runs about $88 street, the BL660 about $120 to $139, and both shift $10 to $20 with sales. The premium pays for itself with daily cup use; otherwise the BL610 is better value.
Design and Build Quality
Both bases are heavy and built for daily use, and the BL660's travel cups survived a heavy drop. The parts we watch first are the BL610's lid spring and the BL660's carafe handle.