Tech and meta levels
These three terms are all indicators of the quality of an item or ship hull and all mean different things. The definitions also differ whether the item is a module, ship or rig.
Modules
Civilian Modules
Civilian Modules are a special case and are only mentioned here for completeness. You should NEVER consider fitting a Civilian Module except in the Tutorial Missions and on your trusty Rookie Ship. Those modules are useless except for educational purposes.
Tech 1 Meta 0
These are the basic modules that can be dropped by NPC ships or manufactured by players from blueprints seeded on the market by NPCs. Meta 0 modules have no Meta level attribute visible in their attributes. They have generic names based on their type such as "1MN Afterburner I".
If someone offers you a "meta 0" duel, they mean a duel in a Tech 1 ship with only this type of module installed.
Tech 1 Meta 1-4
These are dropped by NPC ships and are not manufactured by players. The higher the meta level the better quality the item. Higher meta level items are more effective and usually have lower fitting requirements as well, but this is not always the case. Meta level 1-4 items do not require more skills to use than meta 0. Because of their better performance higher meta level modules will have a higher price on the market. These modules have more colorful names such as "Y-S8 Hydrocarbon Afterburner I". These modules are sometimes called "named" modules.
Tech 2
Shortened to "T2", these modules are manufactured by players through the slightly complicated Invention process. T2 modules are usually more effective than Tech 1 Meta 4 modules, but sometimes they are the same. T2 modules are never less effective than meta 4 modules. Tech 2 modules often require more skills to use than Tech 1 modules, and they usually take more CPU and/or Powergrid to fit. T2 modules have a meta level of 5 in their item attributes.
When deciding whether to use a Tech 2 module, make sure to compare it to a Tech 1 Meta 4 module before making the purchase. In some cases the meta 4 module has the same performance with lower fitting requirements.
Faction
Faction modules are equal or superior to Tech 2 modules and are purchased from Loyalty Point stores either as items or blueprint copies. These items will have a meta level of 5 or higher in their item attributes. They have names based on their faction such as "Caldari Navy Ballistic Control System". These modules are not listed on the general market, but can be bought in contracts.
Deadspace and Officer
Deadspace and Officer modules are dropped in deadspace complexes and from rare named enemies. These are the best modules and as such are very expensive. These items typically have a meta level of 9 or higher in their attributes. Deadspace modules have names based on their faction and quality such as "Pithi B-Type Large Shield Booster". Officer modules are named after the NPC they drop from, such as "Estamel's Modified Invulnerability Field". While officer modules are usually better than deadspace modules, this is not always the case; always check the attributes before you buy. These modules are not listed on the general market, but can be bought in contracts.
Video lesson on Meta Levels
A video introduction to meta levels of modules can be found here: http://www.youtube.com/watch?v=U5ZV4nmi4t4
Ships
Tech 1
Tech 1 ships such as the Rifter are bought from NPCs or manufactured by players from blueprints seeded on the market. Within ship types there are "tiers". For example among minmatar combat frigates the tier 1 ship is the Slasher, the tier 2 is the Breacher and the tier 3 is the Rifter. This does not necessarily mean that the Rifter is better at everything than the Breacher, for example the Breacher performs better at long range, however higher tier ships usually have better performance, more slots and more CPU and Powergrid, and are more expensive. The tier of a ship is not shown in game as an attribute, it can only be inferred from stats and production cost.
Empire Faction
Empire faction ships such as the Imperial Navy Slicer are bought from the loyalty point stores of empire factions, such as the Gallente Federation Navy or Minmatar Republic Fleet. They are obtained as either complete ships or as limited run blueprint copies. They can then be sold on the market by players. Empire faction ships are more powerful but much more expensive than Tech 1 ships, but are normally less powerful than Tech 2 or Pirate faction ships. The main attraction of empire factions ships is that they do not require more skills to use than normal Tech 1 ships, making them attractive to young characters with ISK to spare.
Tech 2
These ships are manufactured by players through the slightly complicated Invention process. They are usually more powerful and slightly cheaper than Empire faction ships, but have high skill requirements to use. As well as better performance and bonuses, T2 ships have increased damage resistance, making them tougher.
Pirate Faction
These ships are bought from pirate faction loyalty point stores. They can then be sold on the market by players. Pirate faction ships require two spaceship command skills to use (for example the Dramiel requires Minmatar and Gallente frigate skills), but do not require high levels in them, making them considerably easier to train for than Tech 2 ships. Pirate ships typically have equal or better performance to Tech 2 ships, but cost more.
Tech 3
The only class of Tech 3 ship in the game are Strategic Cruisers. Tech 3 ships are constructed with Sleeper components that can only be found in wormhole space, and as such are very expensive, but they are the most powerful ships in the game for their size. T3 ships have similar skill requirements to fly as T2 ships.
Rigs
Tech 1
Tech 1 rigs are made from materials salvaged from Tech 1 player or NPC ships. They are made from blueprints seeded on the market by NPCs. Rigs do not have meta levels and there are no subdivisions of quality other than their Tech level.
Tech 2
Tech 2 rigs are made from materials salvaged from Tech 2 player ships. As such they are an order of magnitude rarer and more expensive than T1 rigs.