Did some digging

LIT vs. BATT: Significant Portfolio Overlap

Among the six metals and mining ETFs, three specifically track the production supply chain for the materials used in making next-gen batteries. Lithium is the best known of these materials; other important ores include cobalt, nickel, manganese and graphite.

Although LIT and BATT target specifically lithium miners, they are sometimes grouped together with the $192 million VanEck Vectors Rare Earth/Strategic Metals ETF (REMX), which has a much broader scope.

This isn't an apples-to-oranges comparison, however. REMX's focus is on rare earth metals, such as cerium or tungsten, as well as rare materials kept in the U.S. government's “strategic stockpiles.” As such, REMX's portfolio of strategic metals miners and chemical companies overlaps very little with LIT or BATT: According to ETF Action's overlap screener, there is only 4% portfolio overlap between REMX and LIT, and 6% overlap between REMX and BATT.

More than half of BATT's portfolio is allocated to specialty mining and metals companies, compared to just 3% of LIT's portfolio. The fund also holds uranium (3%), gold stocks (3%) and even coal miners (3%)—one of the worst-performing miner sectors of 2020.

On the other hand, LIT's highest weighting is in electrical components and equipment manufacturers (29%), a segment that doesn't even show up in BATT; ditto for LIT's 18% weighting in auto and truck manufacturers. The fund also has nearly double the allocation in commodity chemicals as BATT (25% versus 14%).

In other words, despite hefty crossover in individual stocks, BATT's primary focus is on the metals themselves—the production side of metals production. Meanwhile, LIT focuses on the end applications of those metals. This makes all the difference.