i looked up the specifications of the FZ7 here
Panasonic DMC-FZ7 Review: 1. Introduction: Digital Photography Review and the 35mm equivalent focal length is 432mm. for DSLRs, the 35mm equivalent focal length is 1.5 x the focal length. therefore for the tamron it is 375mm at its longest. which is why the picture is more "zoomed" in on the FZ7.
most likely when you are shooting things far away, you are experience some camera shake. because the panasonic is faster (has a lower f-stop number at the end of the zoom) 3.3, it will probably be able to take pictures with shorter shutter speeds. with the dslr + tamron, at the end the fastest aperture is 6.3, so it will need a longer shutter speed and will be even more susceptible to blur.
honestly, the FZ7 has excellent optics and it will be very expensive to get something better on a DSLR at the extreme long end.