No, they are differents, see part numbers below:
p615
FC 4446 1024 MB (4 x 256 MB) DIMMs, 208-pin 8 ns DDR SDRAM
FC 4447 2048 MB (4 x 512 MB) DIMMs, 208-pin 8 ns DDR SDRAM
FC 4448 4096 MB (4 x 1024 MB) DIMMs, 208-pin 8 ns DDR SDRAM
FC 4449 8192 MB (4 x 2048 MB) DIMMs, 208-pin 8 ns DDR SDRAM
p630
FC 4451 1024 MB (4 x 256 MB) 208 pin 8 ns DDR SDRAM DIMMs
FC 4452 2048 MB (4 x 512 MB) 208 pin 8 ns DDR SDRAM DIMMs
FC 4453 4096 MB (4 x 1024 MB) 208 pin 8 ns stacked DDR SDRAM DIMMs
FC 4454 8192 MB (4 x 2048 MB) 208 pin 8 ns stacked DDR SDRAM DIMMs
Regards,
Okano