Fastboot is a command line underlying the download mode which itself is a method of updating stock ROMs. Recovery is a whole other mode used to flash ROMs, Kernels, recovery, updates and whatnot. All the modes are important. Sometimes manufacturers block the modes to prevent unlocking, Rooting and such. It's what I know. Didn't go into more details though. Search around to find more.
If they were self explanatory do you think he would be asking for clarification? Try not to make anyone on these boards feel like they don't belong because they ask what appears to you to be self explanatory question it only discourages some from getting answers they must need.
Fastboot is a protocol that can be used to re-flash partitions on your device (update the flash file system in Android devices). It is this small tool that comes with the Android SDK (Software Developer Kit), which is an alternative to the Recovery Mode for doing installations and updates.
Download Mode is a state your phone can be in that allows you to flash firmware through Odin or other desktop development software.
Recovery refers to the dedicated, bootable partition that has the recovery console installed. A combination of key presses (or instructions from a command line) will boot your phone to recovery, where you can find tools to help repair (recover) your installation as well as install official OS updates, custom ROMs and make a backup of your phone.
Download Mode is a state your phone can be in that allows you to flash firmware through Odin or other desktop development software.
Recovery refers to the dedicated, bootable partition that has the recovery console installed. A combination of key presses (or instructions from a command line) will boot your phone to recovery, where you can find tools to help repair (recover) your installation as well as install official OS updates, custom ROMs and make a backup of your phone.
