What is difference between partially penetrating stream and fully penetrating stream?
Streams that are shallow relative to the thickness of the aquifer in which they lie. Such streams often are referred to in the literature as partially penetrating streams. Most streams are partially penetrating streams. Seepage between a partially penetrating stream and the contiguous aquifer occurs both horizontally and vertically through streambank and streambed materials.

Image Source:USGS

There are a few streams that are deep enough to penetrate the full thickness of the aquifer in which they lie. Such streams often are referred to fully penetrating streams. Seepage between a fully penetrating stream and the contiguous aquifer occurs horizontally through streambank materials.

Image Source:USGS