What is the main difference between a Blade Server with any normal Standard Server machine?

Computing power has evolved over the years. Blade servers are currently the most efficient computer devices and are often used by modern businesses as the backbone of the office computer system. Blade servers are gaining in popularity over the rack mounted servers in large office operations. Both provide similar computing power although the devices differ in some key ways.   Rack-mounted servers are computers that contain all the components necessary for operations. Plug the rack mounted server into a standard electrical outlet and connect the network cables and the device is operational. The rack mounted configuration allows the device to be mounted in a computer hardware rack, usually 19 inches in width, although the devices could sit on a table or desk with similar results. Blade mounted servers do not contain all the components of a computer and must be mounted in a blade enclosure which includes power supplies and networking components. The blade enclosure can mount in a rack for ease of operations.   While each system has its advantages the rack mounted servers often offer greater flexibility. The blade enclosure commonly includes a single power supply and cooling unit as well as several other components that are shared among the blade units. The rack mounted servers each operates with its own power supply unit and cooling system and other components allowing the user to configure each rack server unit to the specific needs of the operation.   The single power supply of the blade enclosure may offer some advantages including easier integration with an uninterrupted power supply unit to provide continuous service during power outages. However, the single power supply serving multiple blade servers is a possible point of failure that can render an entire system operational.   Updates to rack servers can include adding more memory or replacing other components within the server. Blade servers are commonly fully integrated board and any upgrade usually involves replacing the blade unit within the blade enclosure. Failing parts within, such as memory, can also be replaced without scrapping the entire rack server. Think of these as computers that can be repaired rather than components of a blade system that would need to be replaced.   Rack mounted servers continue to be the most cost effective computer network option for small to medium sized operations. The cost of a single rack mounted server usually is more economical than a blade enclosure and one or two blade units. For this reason, many businesses start with rack mounted systems and many stay with those proven systems as they grow.  

The main difference is on the level of management that through a management software you can manage the enclosure with its contents on the level of servers , and the fabric interconnects that is used to connect the server with the network and SAN beside that the cabling in case of blade servers are less comparing by rack mount servers

Tower Servers are the normal boxes (in appearance) you would have seen in Visio Diagrams. Of course they are very powerful & have bundled software tools to manage them. The problem with Tower Severs is the space they occupy, management personnel they require, and cost of operating them (power, network, etc.).

Rack Servers are servers mounted inside a Rack (something like we normally use to manage our letters, office files, etc.) Major Racks available out there adhere to an IEEE standard and are measured in rack units or “U’s” (each U is 19” wide and 1.75” tall). So a rack server size is typically in multiplication of these “U’s”. Motivation here is to scale vertically than horizontally with more compact physical servers. In addition to this, there are many other electronic devices which adhere to this IEEE standard for instance – Rack Consoles, SAN devices, Power Backup devices, etc. Advantage being that you can fix them into rack as well along with your servers. Not to mention that the hardware vendors (Dell, HP, IBM, etc.) provide additional software tools that help you effectively manage these servers and in some cases the supported devices also.

Blade Servers are an additional level of innovation on top of Rack Servers. Blade Servers are typically placed inside a blade enclosure, and together they form a blade system. A Blade system normally meets the IEEE standard of Rack Units, which means that the entire Blade system can be placed inside the rack along with other electronic equipments. The benefits of blade enclosure includes hot plugging (normally blade servers have a handle attached to them, for transferring them in and out of the blade enclosure – it’s an easy way of identifying them) and stripped modular design (e.g. shared network ports, power connections, switches, etc.). For instance the hardware we ordered allows us to pack 16 blade servers inside a 10U space. I remember meeting an Oracle Consultant few months back where he was touting about a server with no disk. Such scenarios are possible (and are cheaper) by coupling a blade system and SAN storage. All these boils down to further space reduction, cost savings (power, administration staff) & easy management. Bundle this with Virtualization and you have a very powerful infrastructure at your disposal.

Main Difference is Normal Standers server has its own Power and Cooling with individual management. Blade servers are fixed to blade enclosures witch manage power/cooling/management centrally and they share a common I/O out through the enclosure I/O Bays.