How are you arriving at double the price? 16-CPU-core Mac Studio with storage upgrade to 1TB and RAM upgrade to 128GB comes out to $3,700. Add $700 if you want to upgrade to the 28-core CPU (there’s nothing directly comparable to the DGX Spark’s 20-core CPU).

None of this speaks to the actual GPU performance. The only spec the DGX Spark webpage mentions is “1,000 FP4 TOPS”.