Consider the following ficititious service offerings from your ISP which honors Net Neutrality.
Package 1(NN-Entry Level): You get 1Mbps connection to your home. You will be charged $29.99/month. You are free to use the bandwidth the way you want, for example you can browse google, connect on myspace, signup for vonage VOIP service, download podcasts using itunes, etc. Your traffic is not discriminated.
Package 2(NN-Premium): You get 5 Mbps connection to your home. You will be charged $59.99/month. You are free to use the bandwidth the way you want, as explained in package 1. But along with that, your ISP offers you a high quality VOIP service (better than Vonage for example), unlimited Video hosting service, an alternative to itunes, a free 2GB email service etc. Your traffic is not discriminated either. Your browsing experience will be superior due to higher bandwidth and other services offered may be atleast on par with what is available on the internet. For example, their video blog hosting service is better than youtube.
This is IDEAL tiered internet (with Net Neutrality). Your experience is different with different packages. You get lot more services offered by your ISP with premium package. Also you pay more, ofcourse. But the most important thing is your traffic is not discriminated, only your bandwidth is limited. You pay more, you get more services along with bandwidth. But within your 1Mbps bandwidth, you can use it whatever way you like it.
Now if your ISP does not consider net neutrality and offers tiered internet, that means:
Package 1(No NN-Entry Level): You get 1Mbps (not guaranteed) connection to your home. You will be charged $29.99/month. You are NOT free to use the bandwidth the way you want, for example you can NOT use completely or it will be slow searching in Google, but can use search engine provided by your ISP for faster results. You can not connect to myspace or connection will be slow if you connect to myspace and will be faster if you connect to a similar website hosted by your ISP. You can not use Vonage. You can not download video. You can not possibly download music streams aswell. In effect, Your traffic to certain sites or services is either discriminated or completely banned.
Package 2(No NN-Premium): You get guranteed 2 Mbps connection to your home. You will be charged $59.99/month. You are free to use the bandwidth the way you want, as explained in above while honoring net neutrality (NN-Premium).
This is how telecom/ISP companies are planning to offer so called tiered internet.
Compare this to what you get at USPS to make it much relevant. You get Over Night Guaranteed (Express) and 2-3 day shipping (Priority Mail) or general (First class). These are three tiers of shipping services available to you. Obviously, the overnight Express service is faster and expensive while general (Frist class) is cheaper and slower. This is tiered service.
Net Neutrality means, which ever shipping service you choose, you are free to send letters or packages to who ever you like, as long as they are within the weight limits (compare bandwidth here in for internet usage). USPS will not restrict you to send letters only to a certain people or send only certain type of documents.
If USPS becomes like your telecom/internet service provider, who do not honor net neutrality, you still get all tiers of services ( express, priority and first class). USPS restricts you to send documents only to certain people, or only certain type of documents can be sent. Or if you send certain documents, which are restricted, the package will be shipped late. Your packages are discriminated based on what they contain and where they are going, saying USPS owns the shipping trucks and shipping systems . This is what telecom/internet service providers are trying to/will definitely do if netneutrality is not imposed.
You can read a lot more about Net Neutrality at www.savetheinternet.com's blog : http://www.savetheinternet.com/blog/