In terms of motherboard support, there is no change, both the S and the Plus version support Mini-ITX to ATX form factor motherboards. Storage support is almost the same, there's room for two 2.5" SSDs and two 3.5" HDDs. The Aquarius S even allows the mounting of an additional 2.5" SSD on the rear panel.
The biggest difference between the cases is that the Plus model supports a 360mm long video card whereas the S version is limited to 320mm. Fan support is also reduced, the Plus supports a maximum of ten 120mm fans whereas its more compact brother supports a maximum of five fans.
The Aquarius S is designed to really show off your hardware -- it has a large tempered glass front and side panel. Based on the specification sheet, RGB LEDs are not included with the case but the I/O panel does have an RGB LED switch. Pricing and availability is unknown.
Elegant and Easy Display Design Strong and Sophisticated Chassis Structure Crystal Clear Front and Left Tempered Glass Design Superior Airflow and Ventilation Design Easy SSD/HDD/PSU Installation Easy Cable Management Multiple Cooling Fan placement up to 5 x 12cm Fans Liquid Cooling Radiators Compatibility : Top 240/280mm, Bottom 240/280mm and Rear 120mm