X5-2000 (Hybrid Standard):
2x 400GB SSD - used primarily for Erasure Coding write acceleration
12x 1TB/2TB/4TB/8TB/10TB/12TB NL-SAS = 12TB/24TB/48TB/96TB/120TB/144TB raw capacity

X5-2500 (Hybrid Accelerator):
1x 3.8TB/4.0TB NVMe PCIe
2x 400GB SSD - used primarily for Erasure Coding write acceleration
12x 1TB/2TB/4TB/8TB/10TB/12TB NL-SAS = 12TB/24TB/48TB/96TB/120TB/144TB raw capacity

X3-2000 (Hybrid Standard):
1x 400GB SSD - used primarily for Erasure Coding write acceleration
8x 1TB/2TB NL-SAS = 8TB/16TB raw capacity

X3-2500 (Hybrid Accelerator):
1x 960GB 2.5" PCIe SSD (U.2) or 1.6TB NVMe PCIe
2x 400GB SSD - used primarily for Erasure Coding write acceleration
8x 1TB/2TB NL-SAS = 8TB/16TB raw capacity

X5-6000 (All-Flash Standard):
8x 400GB/480GB/800GB/960GB/1.6TB/1.9TB/3.8TB = 3.2TB/3.8TB/6.4TB/7.6TB/12.8TB/15.3TB/30.7TB raw capacity

X5-6500 (All-Flash Accelerator):
1x 1.6TB NVMe PCIe
8x 400GB/480GB/800GB/960GB/1.6TB/1.9TB/3.8TB = 3.2TB/3.8TB/6.4TB/7.6TB/12.8TB/15.3TB/30.7TB raw capacity

X3-6000 (All-Flash Standard):
8x 960GB/1.9TB/3.8TB = 7.6TB/15.3TB/30.7TB raw capacity

X3-6500 (All-Flash Accelerator):
1x 960GB 2.5" PCIe SSD (U.2) or 1.6TB NVMe PCIe
8x 960GB/1.9TB/3.8TB = 7.6TB/15.3TB/30.7TB raw capacity

There is no difference in storage capacity options between Pivot3 X-series HCI appliances and Pivot3 X-series Storage appliances.