Look at the Plymouth Rock to the right of Light Sussex in last photo. The comb is distinctly pale orange. No red what so ever. That is a pullet all day long and only being determined by the comb. With single comb birds the males combs will outgrow the females and start turning red. Looking at the Sussex again I could hazard a guess to the cockerels. But I'm looking at a photo and lighting, tints of color that aren't there etc can make them deceiving. Your right there, look at the comb. If any red what so ever then cockerel. It starts showing at 4 weeks and sex is very apparent in 5 weeks then down right obvious at 6 weeks. I say this for single comb birds only. Pullets wont have an red until point of lay- 18+ weeks old; again, single comb birds.
There are other hints as well. Your first photos I would have swayed to cockerel based solely on the legs size and stance of the birds. Cockerels will have honking legs compared to pullets, though there are some stout pullets, and the legs will be longer making the bird look much leggier than it's breed brood mates. This is by no means as reliable as looking at the comb but pretty accurate. I've 90% sex accuracy with one week old chicks if they are the same breed ad hatch mates. Solely through observation of stance, leg size and perhaps a few traits specific to breed. Comparison and finding which are not like the others type thing. It's really not hard.
Need to correct- more like 80% accuracy after first week then 90% after 2nd week. At 5 weeks and aid of comb your up to 98%. There will be some that elude you, late bloomers and what not. This past year I had 4 cockerels and 10 pullets at 3 weeks, 5 cockerels and 9 pullets by 6 weeks. It took nearly 8 weeks before that last cockerel truly showed himself or until I noticed somehow we had 6 cockerel so h to recount the flock and sure enough still only had 14 total. This is a small sample size flock I started this past spring but the accuracy holds true when hatching 20 and 30 chicks at a time in years past.