Difference between "Serial Programmer" and "ISP serial programmer"

Hi all, I'm a newbie in Atmel world, so I'm still trying to understand... Imagine I have a PC with Linux and a serial port. As I understood, I can program an Atmel AVR (without bootloader) through the serial port but I find in internet two kind of programmers: 1) Serial programmers: very simple and cheap (few components); 2) ISP(In System Programmer) serial programmers: built using micro-controllers (Atmel) loaded with certain software.

Could someone explain to me the difference , and what kind of software is loaded in ISP serial programmers?

Thanks. Stroccia

stroccia: I'm a newbie in Atmel world, so I'm still trying to understand... Imagine I have a PC with Linux and a serial port. As I understood, I can program an Atmel AVR (without bootloader) through the serial port

No, the chip needs a bootloader.

This is the function of a bootloader - to allow you to program the chip with just a serial port.

A "serial programmer" is a device programmer that connects to your PC using the serial port. an "In-circuit Serial Programmer" (ISP) is a device programmer that connects to the AVR via the ISP pins. A programmer can be both - connecting to the PC via a serial port and connecting to the AVR via ISP (and this is pretty common, especially if you include USB/Serial converters as "PC Serial Ports"), or it can be neither, like a high-voltage parallel programmer that connects to the PC via USB and to the AVR in parallel programming mode.