Taste-wise, is there a difference between tomato from a blender vs. chopped tomato?
It may depend on how much blending they got.

I find that if you blend them for too long or too fast, you strip the 'jelly' part from the seeds, then the seeds themselves start to break up.  That tends to make it bitter, &amp; I suspect that could be what you're tasting.

My standard trick to homemade sieved tomatoes is first I rough chop them - you really don't need much more than cutting them in half [If you do them whole, they tend to go pop]. Then I microwave them just long enough to heat them through &amp; start to soften - depending on quantity you might need to give them a bit of a stir a couple of times. This doesn't need to be very thorough &amp; they don't need to be completely evenly heated.

That should soften them up just enough that you can blend them for just a few seconds &amp; not risk starting to grind the seeds.

Push through a sieve with a ladle &amp; you're good to go.

I would really only tend to go to this kind of effort if my recipe needed a kilo of tomatoes, rather than 3 or 4. For just a few, I'd simply chop them finer &amp; no-one will ever spot the rolled up skin segments.