As per the heading is there really that much difference between them and are they worth the extra.

I've done quite a few searches comparing one to another and a number of the results you get back are reviews that are possibly sponsored / biased towards up-selling products which is beneficial for the company so thought I'd ask the real people and everyday users for an honest opinion in here.

A lot of the comments seem to generally refer to having an extra gear and have seen things like "Tiagra's worth the jump up from Claris because of the extra gear" and "the new Tiagra is the old 105's before they jumped to 2 x 11" ... but in a market whose latest trend seems to be 1 x 11 does having 1 extra cog on the cassette make a difference when even the Claris is 2 x 8 totaling 5 more than the 1 x 11.

Where you may have the same model but with different specs / price points I'm probably more tempted to go one up from the bottom rung with Sora rather than Claris as this can often be the entry point for hydraulic rather than mechanical brakes ... but the frame's are often exactly the same just with different colours / graphics so what else might you expect jumping up from there and is the gear change really that much smoother it justifies the extra cost.