SD Card

SD

-- Size : Width * Length * Thickness (32mm * 24mm * 2.1mm )
-- Weight:  Approx. 2g
-- Operating Voltage : 2.7 - 3.6V
-- Write-protect Switch : YES
-- Terminal Guards : YES
-- Number of Pins : 9 pins

The SD Memory Card or Secure Digital was introduced in 2001 by SanDisk Corporation, Matsushita (Panasonic) and Toshiba. The SD Memory Card was based on the MultiMediaCard, MMC, memory card standard and has almost the same form factor, the only differences are that the SD memory card is slightly thicker and has a write protection switch. Since MMC cards are thinner than SD Memory Cards they can be used in all SD Memory Card slots but not vice versa.

The SD Memory Card is today the most common used memory card. It can be found in most digital cameras, PDAs and in many other electronic devices. The SD Memory Card slots can be used for more than flash memory cards. The SDIO, Secure Digital In & Out, is the general name for the many expansion modules that can be found in the SD Memory Card's form factor. SDIO modules can be inserted in the slot and be used for other functions like Bluetooth adapters, GPS receivers, digital cameras, TV tuners, etc.

There's another new format of SD Card called "SDHC", you can click here to read the guides on it.

miniSD Card

miniSD

-- Size : Width * Length * Thickness (20mm * 21.5mm * 1.4mm )
-- Weight:  Approx. 1g
-- Operating Voltage : 2.7 - 3.6V
-- Write-protect Switch : YES
-- Terminal Guards : NO
-- Number of Pins : 11 pins

MiniSD compability list for popular brand:

Nokia: 
N93、N92、N80、N71、N73、E70、E61、6265、6268、6270、6280、6288、6708

Motorola:
E725、Q、MPx220

The miniSD was introduced in 2003 by SanDisk Corporation in cooperation with Matsushita (Panasonic) and Toshiba. Later in that year the miniSD format was adapted by the SD Card Association as the second form factor memory card in the Secure Digital family.

The miniSD card was developed to meet industry demands for downsizing mobile phones. It is only 37% the volume of an SD Memory Card. Despite its tiny size, the miniSD card offers all the benefits of the original SD Memory Card, including copyright protection. By inserting the miniSD card into the miniSD adapter, you can share a variety of digital data among standard SD-enabled products.

microSD Card also known as Transflash

microSD

-- Size : Width * Length * Thickness (11mm * 15mm * 1mm )
-- Weight:  Approx. 0.6g
-- Operating Voltage : 2.7 - 3.6V
-- Write-protect Switch : NO
-- Terminal Guards : NO
-- Number of Pins : 8 pins

MicroSD compability list for popular brand:

Nokia: 
N75、N95、E50、E65、3250、5200、5300、5500、6085、6125、6131、6133、6136、6151、6233、6234、6300、7373、7390

Motorola:
E398、E770、SLVR L7、RAZR V3i、RAZR V3x、RAZR maxx V3、RAZR maxx V6、RIZR Z3、ROKR E3、KRZR Klm、K1、V361、V975

Samsung:
SGH-D510、SGH-D600、SGH-D820、SGH-D830、SGH-D840、SGH-D900

SGH-E250、SGH-E390、SGH-E570、SGH-E770、SGH-E870、SGH-E890、SGH-E900

SGH-i300、SGH-i320N、SGH-P850、SGH-T809、SGH-X700、SGH-X800、SGH-X810、SGH-Z300、SGH-Z400、SGH-Z500、SGH-Z700、SGH-Z710

* Please take note not all the phone with microSD slot supports up to 2GB, so far the following phones have been mentioned by users that they do not support the 2GB TransFlash/MicroSD:

SGH-D600, SGH-D900

TrashFlash, formerly known as T-Flash, was introduced by SanDisk Corporation in 2004 as the world's smallest memory card, approximately the size of a fingernail. TransFlash was specifically designed for being used in mobile phones. Motorola was the first mobile phone manufacturer to adapt the TransFlash memory card standard.

In the 3rd quarter of 2005 TransFlash was adapted by the SD Card Association as the third form factor memory card in the Secure Digital family, after SD Memory Card and miniSD. After the adoption, TransFlash changed name to microSD. The microSD has exactly the same dimensions and specifications as the TransFlash and therefore both memory cards are completely compatible to each other.

Today the microSD is the most common used memory card in mobile phones and the SD Card Association's objective is to make microSD a de facto memory card standard for all mobile phones. All TransFlash and microSD cards always come with a SD Memory Card adaptor, which makes them compatible to all SD Memory Card slots. The microSD is about 10% in size compared to SD Memory Card and about 30% compared to miniSD.

MicroSD / TransFlash is one of the smallest memory card formats available; a MicroSD / TransFlash card is about the size of a fingernail. It was designed to be smaller than competing formats and to reduce the overall size of mobile phones going forward.

You can contact me if you do have any doubts on the compatibility issues. I do hope this guide is helpful and do vote for me, thanks a lot ;)