Hello,
You are right. Just read this page:
https://www.travelchinaguide.com/attraction/beijing/summer/back_lake.htm

that is correct. yuanming yuan is located near to yiheyuan and both are very big. Do not try to see both in one day unless you like walking for about 8-10 hours.

yiheyuan(summer palace) has more people and more to view, kunming lake is one part. and yuanmingyuan is much less visited because it hasn't much to see other than ruins from the wars and many little lakes.

i still prefer yuanming yuan because I've lived here a long time and don't enjoy massive crowds. which you will see here in Beijing during the tourist seasons.