How to identify different ion exchange resins?

The question is too broad. It’s possible to distinguish between large pores and gel resin visually, and it’s perhaps possible to differentiate between cationic and anionic resins as well; ultimately, analysis is what’s needed.

Step 1: ① Take 2 mL of the resin sample and place it in a 30 mL test tube, then remove the surface moisture from the resin. 　　②Add 5 mL of 1 mol/L HCl, shake for 1–2 minutes, and remove the supernatant from the upper part of the resin. Repeat the operation 2 to 3 times. 　　③Clean with pure water, shake, and then suction out the clear liquid from the top. Repeat the operation 2 to 3 times. 　　④Add 5 mL of 10% CuSO4 solution and shake for 1 min. Press ③ to thoroughly clean with pure water. 　　Step two. 　　After the first step of treatment, if the resin changes color (to light green), add 5 mol/L NH4OH. Add 2 mL of OH solution, shake for 1 minute, rinse thoroughly with pure water before observing. 　　If the color of the resin deepens (to dark blue) after the above treatment, it is a strongly acidic cation exchange resin. If the color of the resin remains unchanged (still light green), it is a weakly basic anion resin. 　　Step three. 　　After the first step of treatment, if the resin does not change color, proceed as follows: ① Add 5 mL of 1 mol/L NaOH, shake for 1 minute, and then thoroughly wash it using the pouring method. 　　②Add 5 drops of phenolphthalein, shake for 1 minute, and rinse thoroughly with pure water. 　　③After the above treatment, if the resin is red, it is a strongly basic anion exchange resin. 　　Step four. 　　After the third treatment step, the resin remains colorless; proceed as follows: ① Add 5 mL of 1 mol/L HCl, shake for 1–2 minutes, and then wash with pure water 2–3 times. 　　②Add 5 drops of methyl red, shake for 1 min, and rinse thoroughly with pure water. 　　③After the above treatment, if the resin is peach-colored, it is a weakly acidic cation exchange resin. After treatment, if the resin does not change color, it has no ion-exchange capacity.

Your question is too broad. There are so many types of resins, each with different functions. Do you want to distinguish it with the naked eye, or what?