Generally, pure Web applications (of any type) fail to enjoy the same full feature set and robust functions of their client/server cousins. Quite simply, pure Web applications are not as mature as client/server systems. However, that doesn't mean they aren't worth considering. On the contrary, pure Web products have come a long way in the last few years and frequently what they lack in functionality, they make up for in simplicity and ease of use.
And yes, you can call them eCRM applications if you like. However, I typically think of the customer-facing applications as eCRM, but in this jargon-laden industry, anyone is free to create and redefine these concepts.
Finally, what's better, PeopleSoft version 8 or Siebel 7? It's too complex a question to answer in a paragraph or two. More importantly, CRM is all about process flows and workflow integration (within a customer-centric domain). Either application could serve your firm extremely well if you pay close to the business problem first, process integration second, and the technology last. I don't mean to minimize the importance of your question, but only after understanding your business needs will you be able to determine which application is better suited to your situation. But, the decision is less critical than the efforts you need to spend understanding and integrating the functional requirements.