Is the word 感觉 not redundant?
&quot;感&quot;, more objective, the feeling that surroundings impose on you. &quot;冷感&quot;, &quot;热感&quot;
&quot;觉&quot;, more subjective, the feeling from your heart (/mind/senses) about surroundings. &quot;味觉&quot;, &quot;视觉&quot;
Yes, they are quite similar, and in some cases, they both mean &quot;feel/feeling&quot;.
But in some other cases, you can find the difference by comparing &quot;感到&quot; and &quot;觉得&quot;.
&quot;我感到房子在摇动&quot;, I have a feeling that the house is shaking.
&quot;我觉得房子在摇动&quot;, I think the house is shaking (maybe not, actually).
In fact, there are quite a lot of chinese words made of characters with similar meaning, like 奔跑/游泳/旋转/图画/增加. Two of the reasons I know:

it can avoid ambiguity with the same pronunciation (which reminds me of the different characters with same pronunciation in Japanese).
it improves the symmetry and fluency of a sentence, as most words in chinese are made of two characters.