Prior to the 2015 Google I/O event this week in San Francisco, details have leaked out that provide hints on what to expect with the Nexus 2015 device and the software to power it -- Android M. Two models are said to be unboxed while the next Android successor is tipped to be a giant leap from Lollipop 5.xx.

It appears that the grand plan by Google this year is to directly challenge Apple by rolling out two Nexus handsets -- that LG and Huawei will assemble -- while matching the fresh killer features that Apple's iOS 9 will soon unpack. Essentially, Android fans will get a whole package that includes a regular-sized smartphone, a monster phablet and a beastly platform engine that supposedly the Android M is. Here are some details about the expected products:

LG Bullhead

As the name implies, the Nexus Bullhead is coming out of LG’s production lines and is likely a repurposed LG G4. The device, according to Android Police, will largely mirror the specs seen with the G4: a 5.2-inch display profile, a 2700 mAh battery and a Snapdragon 808 chip. Somehow, the Bullhead will deliver on most of the speculated component upgrades previously attached with the Nexus 5 2015.

Huawei Angler

In battling with the supersized phones coming from Apple and Samsung, Google is tapping Huawei of China to build a 5.7-inch phablet that at the moment is internally referred to as Angler. This bigger Nexus is the direct replacement for the 5.9-inch Motorola Nexus 6 and will be amply fired up by the Snapdragon 810.

An upsize in build and capabilities, Google’s 2015 jumbo phone will get its energy juice from a 3,500 mAh battery that gives the assurance of longer operating hours in a single charge.

Now with two phones on the horizon this year, the Nexus maker seems bent on putting off a tablet refresh. That means that the HTC Nexus 9 will remain as the tech giant’s flagship tablet for 2015 as “no Nexus tablet is in the works,” Android Police said.

RAM And Battery Efficient Android M

And to go with the Nexus Bullhead and Angler is Android M, which according to 9to5Google will include huge upgrades. But the main focus of the bumps is battery and RAM optimization. Once this refreshed Android version, codenamed Macadamia Nut Cookie or MNC, is out, users can expect smarter use of battery to keep the device going as long as possible.

Also in serious consideration for the overhaul are “trimming down RAM usage, and reducing activity off-charger and when the device’s screen is off,” 9to5Google added.

In all likelihood, Google will allow a sneak peek of Android M at its I/O conference, which kicks off Thursday, thus paving the way for an August rollout. To follow are the new Nexus 2015 smartphones that are scheduled for an October release date.