[Android Q&A, Help & Troubleshooting] rishav754:
yes both are nand device .......now a days flash nand technology is used in solid drives. NAND has so many advantages over NOR technology like higher densities, larger capacities, and lower cost. It has faster erases, sequential writes, and sequential reads.

inner storage has more pins than sd cards . sd card have 8 pins where as internal storage have 16 or may be 32 pins which results into high read write speed . both sequential as well as random read write speed of inner storage are better than sd card .

if you want to know more about random read write speed go to this thread : http://xdaforums.com/showthread.php?t=2742903

i randomly performed a disk marking and got following results .

test performed on 50 mb space

1. inner storage (device micromax canvs hd )'

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CrystalDiskMark 3.0.3 Shizuku Edition x64 (C) 2007-2013 hiyohiyo

Crystal Dew World : http://crystalmark.info/

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* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 34.813 MB/s

Sequential Write : 6.757 MB/s

Random Read 512KB : 34.773 MB/s

Random Write 512KB : 2.992 MB/s

Random Read 4KB (QD=1) : 13.044 MB/s [ 3184.6 IOPS]

Random Write 4KB (QD=1) : 1.079 MB/s [ 263.3 IOPS]

Random Read 4KB (QD=32) : 15.335 MB/s [ 3744.0 IOPS]

Random Write 4KB (QD=32) : 1.143 MB/s [ 279.1 IOPS]

Test : 50 MB [H: 37.1% (671.3/1809.3 MB)] (x1)

Date : 2014/05/15 23:21:18

OS : Windows 7 Ultimate SP1 [6.1 Build 7601] (x64)

2. sony sd card (32 gb class 4)

rystalDiskMark 3.0.3 Shizuku Edition x64 (C) 2007-2013 hiyohiyo

Crystal Dew World : http://crystalmark.info/

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* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 8.725 MB/s

Sequential Write : 3.028 MB/s

Random Read 512KB : 8.715 MB/s

Random Write 512KB : 0.659 MB/s

Random Read 4KB (QD=1) : 2.548 MB/s [ 622.2 IOPS]

Random Write 4KB (QD=1) : 0.247 MB/s [ 60.4 IOPS]

Random Read 4KB (QD=32) : 2.905 MB/s [ 709.2 IOPS]

Random Write 4KB (QD=32) : 0.384 MB/s [ 93.7 IOPS]

Test : 50 MB [E: 16.7% (4.8/28.9 GB)] (x1)

Date : 2014/05/15 23:26:53

OS : Windows 7 Ultimate SP1 [6.1 Build 7601] (x64)

3. pen drive 16 gb hp

CrystalDiskMark 3.0.3 Shizuku Edition x64 (C) 2007-2013 hiyohiyo

Crystal Dew World : http://crystalmark.info/

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* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 19.958 MB/s

Sequential Write : 5.597 MB/s

Random Read 512KB : 22.317 MB/s

Random Write 512KB : 0.997 MB/s

Random Read 4KB (QD=1) : 4.655 MB/s [ 1136.4 IOPS]

Random Write 4KB (QD=1) : 0.012 MB/s [ 2.9 IOPS]

Random Read 4KB (QD=32) : 5.362 MB/s [ 1309.2 IOPS]

Random Write 4KB (QD=32) : 0.013 MB/s [ 3.1 IOPS]

Test : 50 MB [D: 0.1% (0.0/15.0 GB)] (x1)

Date : 2014/05/15 23:42:49

OS : Windows 7 Ultimate SP1 [6.1 Build 7601] (x64)

now you can easily compare the basic difference . i found that random write speed is maximum in case of inner storage which is required for better performance of operating system (refer the link of thread ).

:)