The answer to 'difference between weed control' is that there are two main types of weed control: pre-emergent and post-emergent. Pre-emergent products are applied before weeds germinate and form a barrier to prevent them from sprouting. Post-emergent products are applied after weeds have already emerged and are used to kill existing weeds.
Pre-emergent weed control is typically more effective at preventing weeds, but it requires precise timing and application to be effective. Post-emergent products are more flexible and can be used to target specific weeds as they appear, but they are less preventative. The best approach often involves a combination of both pre-emergent and post-emergent treatments tailored to the specific weed challenges in your lawn or garden.