Dear Kedar. I also have classic records 45rpm reissues of some titles. It is very interesting that you find them very different. They both use the same tapes for origin and same engineer for remastering who is Bernie Grundman. I believe he did not remaster them again and again and they actually are pressed from the same remasters. While some of the classic records are pressed on one sided vinyl with their propriety formula, others afaik are actually pressed at the same pressing plant, RTI. So, wild variations between these is surprising and at my place not evident. Actually Analogue Productions, ORG and Classic Records 45rpm reissues sound very similar.ORG is bad. There is nothing necessarily about 45s only that is better. Classic records 45s are good but that is classic records. In that case you might find 45 better than 33. I did the classical ORG and speaker corners compare to originals, SC and ORG have some common releases. For Albeniz Suite Espanola the Decca SXL is so much better, and it is the first UK edition but earlier editions were in EU. Mendelssohn Deccas are excellent.
This 45 vs 33 is a noob thing, sorry, audiophiles think that 45 is more information. Sonic quality is based on the master tape, the engineers and the equipment that is used. That's why when any of this is changed, the sonics drop.
45rpm is not a noob thing, it is physical advantage in terms of sound quality, no questions about that! However, it always comes down to the actual recording and mastering. Being 45rpm does not guarantee best sound but if we have the same master, and we cut at both 33 and 45, 45 will surely sound superior every time.