There might be - depending on cached entries, etc. The second query will be two range queries and a regular query combined into three boolean clauses, while the first one will be six different boolean clauses.
Speed probably won't differ too much for your example, but as the number of clauses grow, the latter will keep the number of sets to be intersected lower than the first one. To get exact data - try it out - your core will be different from other people's cores.
And no, Solr won't preprocess anything. That's handed over to Lucene to do as it pleases, but a range query can be resolved in a different way than a exact field query. There can be entries between the terms given in your pure boolean query, so you can't translate it into a range query and expect the same result, and you can't do it the other way around either - since the field may not be integer (and even integer types differ in how they're being indexed).
The important part is usually that the fq
will be cached separately, so it's usually more important to keep it re-usable across queries.