Databases allow you to search across hundreds, if not thousands of journals and other source material, at one time. They are optimized for this function and usually offer both sophisticated and novice methods for successful searching.
E-journal collections are virtual warehouses that collect and display e-journals easily. They are often publisher-specific. While e-journal collections are searchable, they're not optimized for this function.
A few examples follow:
Databases | E-journal Collections |
Art Abstracts | JSTOR |
PsycInfo | Oxford Journals |
Zoological Record | Science Direct |