iMac Radeon Pro 555 vs 560

[Kelvin_Cheng]

From apple online store, two specs:

• 21.5‑inch iMac with Retina 4K display
  
• Radeon Pro 555 with 2GB video memory,
• 3.6GHz quad-core 7th-generation Intel Core i7 processor, Turbo Boost up to 4.2GHz
  
• 16GB 2400MHz DDR4
  
• 512GB SSD

Price: $2,199

and

• 21.5‑inch iMac with Retina 4K display
  
• Radeon Pro 560 with 4GB video memory
• 3.6GHz quad-core 7th-generation Intel Core i7 processor, Turbo Boost up to 4.2GHz
• 16GB 2400MHz DDR4
  
• 512GB SSD

Price: $2,199


Does this mean Radeon Pro 555 with 2GB video memory has same price as Radeon Pro 560 with 4GB video memory?

I use iMac for iOS development. Which one should I buy?

 

[padams35]

Think of it as a buy-2-get-1-free deal Apple offers on {GPU, CPU, Fusion/SSD} package upgrades. If you intend to upgrade both the CPU and SSD anyway then I can't think of any reason not to take the free upgrade to a Pro 560.