E-gold Vs E-Bullion

Backed by Precious Metals
One of the first similarities, which you will notice right away, is that unlike PayPal, which is email-based currency, both e-gold and e-Bullion are backed by precious metals. E-gold is backed by gold (the primary precious metal), silver, platinum, and palladium, while e-Bullion uses silver and gold only. E-gold and e-Bullion are not related but probably it is the slight similarity in the name, which makes people sometimes confuse them.

Popularity
The popularity factor is one of the most important factors you need to consider when choosing a payment system. It takes two for a transaction, so your choice of payment system largely depends on what the other party accepts as payment or can pay with. Here e-gold comes as the clear leader. With so many sites, which accept e-gold, it is obviously one of the Top 5 payment systems in popularity.

What is more, it is expected that the popularity of e-gold will continue to rise. For instance, recently PayPal froze the accounts of many Get Paid To sites and most of these sites switched to AlertPay, while some started offering e-gold. But here is the catch - you can use e-gold for AlertPay withdrawals/funding, so actually, if you have an AlertPay account, you can choose to transfer money to your credit card/bank account or withdraw to/fund your e-gold account.

e-Bullion is very far from that level of popularity. I have noticed that if a site accepts 7-8 or more payment systems, one of them could be e-Bullion but if there are only 3-4 payment systems, usually e-Bullion is not included on the list, while e-gold is.

Fees and Withdrawal Rules
The fees and withdrawal rules of e-gold and e-Bullion vary considerably. Generally, for small amounts e-gold is the better choice because its fees are lower and it does not require a monthly service fee, as e-Bullion does. The e-Bullion monthly service fee is the dollar equivalent of one-third (1/3) of a gram of Gold, or around $5-7, which for small amounts is really a lot. For small amounts, the monthly storage fee of e-gold is considerably lower than that - 1% annually.
The liquidation fee for e-Bullion is 2% and 3% depending on the type of withdrawal. For e-gold withdrawal fees depend largely on the amount and they generally vary from 1.25% to 5% (plus a fixed fee). If you are interested in learning more about the fees of e-gold and e-Bullion, you may want to check these links: https://www.e-gold.com/unsecure/fees.htm and https://secure.e-bullion.com/fees.php.
Withdrawal rules are other important criteria when comparing electronic payment systems. In terms of choice, e-Bullion is unbeatable. It offers exchanges and withdrawals, while e-gold can be exchanged at specialized third-party exchanges only. To put it simply, this means that if you want to get the money from your e-god/e-Bullion account, it is more difficult to do it for e-gold funds.

For e-gold, the fees you will pay for withdrawal vary a lot depending on the exchange you choose. Additionally, if you want to transfer the money to your bank account, the exchange will most likely charge you separately and the bank wire charges can be as high as $35 or even more. However, this is not much different from the terms of e-Bullion for bank wire withdrawals, where the fees, especially for international users, are very high - $25 + liquidation fee for transfers to a US bank and $40 + liquidation fee for international transfers. Needless to say, these fees make small transfers (I.e. for $20-50) not feasible.

Security
For an electronic payment system security is paramount. In that aspect both e-gold and e-Bullion offer adequate protection. For instance, both systems provide the standard features such as secure login and encrypted communications. I can't say which system has a better security because they apply different means to protect your account.

For instance, with e-gold you can lock the access to your account to your IP, or current browser version. However, as my experience shows, if your browser gets upgraded or your provider changes the IPs, this causes problems for you. Your e-gold account gets blocked and you can't access it. Additionally, if you believe that the computer you are using to access e-gold is not secure and your password can be captured by somebody malicious, you can use the onscreen keyboard to enter your password. The onscreen keyboard randomizes the characters, so it is virtually impossible to capture your passphrase via a keyboard logger.
E-Bullion also offers a lot of security features. They don't have an onscreen keyboard but they use a captcha (which is to stop bots, rather than people, from logging into your account) and they offer CRYPTOCard (costs $99.50), which uses 2-factor authentication (I.e. it matches the checksum of your hardware and your password).

User Interface
Finally, one of the factors one should pay attention to when reviewing electronic payment system is its user interface. Here e-Bullion comes as a clear leader. Its interface has a better design and more features. As you guess, more features usually translate to a steeper learning curve but not in the case of e-Bullion. Its features are arranged with usability in mind and you will not have to spend hours attempting to figure out how to perform a simple operation.

E-gold's interface is also great. It offers fewer features but actually you have everything you need.