Will replacing the MOC3024 with MOC3021 make any change
The answer to your question is "For loads of 10 watts or less; yes, it will work. For loads greater than 10 watts, don't do it."

The MOC3041 is rated for 1 amp, which is ~120 watts at 120 VAC. The MOC3021 is rated for 100 mA, which is ~12 watts. For loads less than this, either unit will work. For loads greater than this, at some point the MOC3021 will fail. Or rather, there is no guarantee the MOC3021 will work at these levels, so don't do it.