.vbp "Object" vs "Reference"

In VBP files, there are "References" and "Objects" as follows:

Reference=*\G{D63E0CE2-A0A2-11D0-9C02-00C04FC99C8E}#2.0#0#..\..\..\WINDOWS\system32\msxml.dll#Microsoft XML, version 2.0
Object={EAB22AC0-30C1-11CF-A7EB-0000C05BAE0B}#1.1#0; ieframe.dll

- What are the differences between these two?
- Why are some dlls referenced via Reference instead of Object or vice versa?
- Where is VB getting the filepath for Object references? The paths aren't specified for them in the VBP, nor does the GUID come up when I search my registry! However, when I load the project, VB tries looking for the dll/ocx/etc at some absolute path (e.g. C:\path\to\dll\ieframe.dll). Where is it getting this path if it isn't in the registry or VBP??!