Similarities

• According to Dyson.com, both the DC17 and the DC25 models have the intense suction Dyson is known for (220 watts) and come equipped with a HEPA filter and the Quick-draw Telescope Reach wand. Another shared feature is the ability to turn the brushbar on and off with the touch of a button, allowing the user to protect hardwood floors from the brushbar then easily segueing back onto carpet.
  
  

The Big Difference

• The single greatest difference between the DC17 and the DC25 is the movement type: The DC17 has the more traditional fixed wheel while the DC25 sports the distinctive Ball, which is designed to make the machine far more maneuverable. The Ball models have a lower center of gravity, allowing them to glide around furniture easily, although they don't get underneath low-standing furniture as well as the fixed wheel models, which can lay nearly flat.
  
  

Size and Capacity Differences

• The DC17 weighs 4.5 pounds more than the DC25, but it also has twice the capacity (its bin holds 0.63 gallons to the DC25's 0.31) and travels farther, with a 35 foot cord granting it a maximum reach of 51 feet. The DC25 has a 24.6 foot cord, with a maximum reach of 40 feet.
  
  

Available submodels

• Although the official Dyson site shows only one DC17 model--the All Floors--third-party vendors offer use-specific submodels such as the Animal for pet owners and the Asthma and Allergy for those with respiratory concerns. DC25 comes in All Floors, Animal, and the limited edition Blueprint, which is supposed to fit underneath low furniture better than the other Ball models.
  
  

Price ranges

• The full retail for the DC17 starts at $449, as shown on the Dyson website, while the DC25 starts at $499. Refurbished models are available from various vendors for less, however. Generally, specialized submodels such as the Animal cost more because they come with extra, use-specific accessories.