Transflash cards were originally developed by SanDisk and have now evolved into what we know as microSD cards. TransFlash and microSD are essenmtially the same, except for SDIO possibilities being added with microSD.
There are a variety of Secure Digital (SD) products available..
Secure Digital (SD) --> Original SD card offering capacities up to 8GB currently.
miniSD --> A smaller form-factor version of the original SD card.
microSD --> Currently the smallest flash memory card on the market.
miniSDHC --> High Capacity version of miniSD card.
microSDHC --> High Capacity version of microSD card.
SD plus --> A form of SD card developed by SanDisk.with USB additions.
Eye-Fi --> An SD card with built in Wifi capabilities of its own.
Gruvi --> A form of SD card developed for content distribution by SanDisk.