try yourself |run program

# create a new list using loop
mylist = [[10,20,30,40,50],[100,200,300,400,500],[1000,2000,3000,4000,5000]]
newlist = []
for innerlist in mylist:
    for item in innerlist:
        if item > 200:
            newlist.append(item)
        else:
            newlist.append(item*item)
    
print("using for loop:",newlist)

# create a new list using comprehension
mylist = [[10,20,30,40,50],[100,200,300,400,500],[1000,2000,3000,4000,5000]]
newlist = [item if item > 200 else item*item for innerlist in mylist for item in innerlist ]

print("using list comprehension:",newlist)

Program Output

using for loop: [100, 400, 900, 1600, 2500, 10000, 40000, 300, 400, 500, 1000, 2000, 3000, 4000, 5000]
using list comprehension: [100, 400, 900, 1600, 2500, 10000, 40000, 300, 400, 500, 1000, 2000, 3000, 4000, 5000]