Google PageRank is calculated using a complex equation. See Table below for full equation. Technorati Rank is calculated based on the number of links from other blogs.
RANK NUMBER
Google PageRank is a number from 0 to 10. Technorati Rank is a number calculated on basis of total incoming links and can vary from 3 to4 million to 1. An increasing number is good for Google Rank but not so for Technorati Rank
UPDATE TIME PERIOD
Technorati Ranking is usually updated as soon as Technorati receives a ping from the page with a link to your page. Google Page Rank is usually updated every three months but may take longer.
Technorati Page Rank has a limit of 180 days. Hence your Technorati Rank will start dropping after this period if no new blogs link to you . Google Page Rank may drop due to other reasons but backlinks do not expire. Hence domains with an older age have a higher rank.
OTHER FACTORS
Internal links affect Google Page Rank but not Technorati ranking. Increasing blog content increases Google Page Rank while having no effect on Technorati ranking. Outbound links decrease Google Page Rank while having no effect on Technorati Rank.