Valley Glaciers:
Valley glaciers, also known as alpine glaciers, are glaciers that form in mountain valleys or high-altitude areas. They are relatively small compared to continental ice sheets and are typically found in regions with high elevations and steep slopes. Valley glaciers flow downhill through mountain valleys and can have varying lengths, ranging from a few kilometers to tens of kilometers.

Characteristics of Valley Glaciers:
- Shape: Valley glaciers are typically long and narrow, with a U-shaped cross-section. This shape is formed as the glacier erodes and carves out the valley floor.
- Flow: Valley glaciers flow downslope due to the force of gravity. The ice in the glacier moves slowly, with the speed of flow depending on factors such as temperature, slope, and thickness of the ice.
- Erosion: Valley glaciers are highly erosive and can carve out deep valleys, sharp ridges, and cirques. They erode the landscape through processes like plucking and abrasion, which involve the removal and transport of rocks and sediments.
- Accumulation and Ablation: Valley glaciers gain mass through snowfall in their accumulation zone, located at higher elevations. As the ice flows downhill, it reaches a point where ablation (melting and sublimation) exceeds accumulation, resulting in ice loss.

Continental Ice Sheets:
Continental ice sheets, also known as ice caps or ice fields, are massive sheets of ice that cover large land areas, typically at high latitudes. They are much larger than valley glaciers and can span hundreds of thousands of square kilometers. The two most prominent continental ice sheets are the Antarctic Ice Sheet and the Greenland Ice Sheet.

Characteristics of Continental Ice Sheets:
- Size: Continental ice sheets are vast in size and can cover entire landmasses. The Antarctic Ice Sheet, for example, covers around 14 million square kilometers.
- Flow: Unlike valley glaciers, continental ice sheets flow outwards in all directions from their central regions. The ice moves under its own weight and spreads horizontally, covering the underlying terrain.
- Erosion: Continental ice sheets are not as erosive as valley glaciers. However, they can still cause significant erosion over time, creating features like fjords, moraines, and drumlins.
- Accumulation and Ablation: Similar to valley glaciers, continental ice sheets gain mass through snowfall in their accumulation zones. However, since they are much larger, the ablation zone is often located near the edges of the ice sheet, where melting and calving occur.

Conclusion:
In summary, valley glaciers and continental ice sheets differ in terms of size, shape, flow, and erosive capabilities. Valley glaciers are smaller, flow downhill through mountain valleys, and are highly erosive. On the other hand, continental ice sheets are massive in size, flow outwards from their central regions, and have a more limited erosive impact. Both types of glaciers undergo processes of accumulation and ablation, but the location of these zones differs due to the contrasting scales of the glaciers.