The first difference is that instead of weighing the 2-hydroxybenzoic acid on scales on a work bench in a beaker as you would in small scale, it is easier and safer to weigh it onto scales, in a plastic bag on the floor. This is easier and safer because the chemical is fluffy so it drifts through the air and could harm anybody who breathed it in. so if it is poured slowly and carefully into a bag then the bag stops it from fluffing into the air and harming anybody. Also the scales are on the floor so that you do not have to lift the large amounts of chemical as it is very heavy.
In small scale preparation of aspirin the 2-hydroxybenzoic acid would then be poured into a round bottom flask with 2 openings. But in large scale it is poured from the plastic bag into a large container that sucks the chemical through a tube up into a container suitable for the reaction to take place. Also the people working on the preparation in large scale will have to be wearing full body protective suits as the chemicals involved are harmful in such large quantities, whereas in small scale you would be wearing a lab coat, goggles and possibly plastic gloves as there is less of the harmful chemical so less danger of damaging yourself or others.
Next the ethanoic anhydride will be added, in large scale, it will be taken from a tank through a tube which will transfer the correct amount, like a burette, into the tank containing the hydroxybenzoic acid. This is different to lab scale work as you would use a small burette to measure the ethanoic anhydride instead, as you